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Concourse 2

The article system


Articles in English form a sub-class of determiners.  If you want the overview first, therefore, you should look at the guide to determiners (new tab).

Articles are unusual determiners in that they cannot stand alone in English and function as pronouns.  Other determiners generally perform both functions as in, e.g.:
    I didn't lose any
    I want that
    I don't have many
    Give me some

but we do not allow:
    *I have the
    *She gave me a

Other languages, incidentally, do not necessarily have a parallel restriction.

There are three articles in English that we consider here:

  1. a / an: the indefinite article
  2. the: the definite article
  3. Ø: the zero article

In what follows, we shall not be considering the negative article no or the partitive article some.


How many possible articles are there?

English does not use the full range of articles (and it is unlikely that any language does) but there are possibilities in all languages and some will use more or fewer of the possible articles to determine nouns.

Here they are, with a few comments:

  1. The indefinite article
    In English this is either a or an but some will include some as a plural indefinite article.
    Example are:
        This is an interesting book
        He came to a halt
        Give me some coins
        We have wasted an hour
        It's a(n) historic moment
    The issue for some learners is that the article an occurs slightly irregularly.
    The general rule is that we use an before a vowel sound, but we use a before a consonant sound and in both cases disregard how the word is spelled because this is a pronunciation issue.  So we get, e.g.:
        an artist
        a sculptor
        a European issue
        an honourable man
    When the /h/ sound is weakly or not sounded, many BrE speakers will also use an instead of a so we have:
        an historic moment
    and some will choose to use an before hotel because the word is quite recently imported from French and the 'h' is not sounded in that language.
    When the /h/ sound is clear, however, the choice falls on a as in, e.g.:
        a horrible experience
    Both a and an are very often reduced to their weak forms and pronounced as /ə/ and /ən/ respectively.
    If, however, the speaker wishes to emphasise the fact that the article refers to only one instance of a specified set of items, then the article is pronounced in its full form as /eɪ/ or /æn/.  In writing, this use will usually be shown as emphatic as in, e.g.:
        That's a reason but not the only one
        That's an idea but not the best one
    In quite a lot of languages which have an indefinite article, it is indistinguishable from the numeral one (and if not the same, then closely related to it).  Unsurprisingly, the article a/an is derived from the word for one in English and is a reduced form of it.
  2. The definite article
    In English this is solely the word the because English does not have alternatives dependent on gender or number so we have e.g.:
        The people all arrived late
        The car went off the road
        The choice is limited

    Again, there is a pronunciation issue.
    The article is pronounced /ði/ before a vowel sound and /ðə/ before a consonant sound, again, regardless of how a word is spelled.  We have, e.g.:
        the apple (/ði.ˈæp.l̩/)
        the man (/ðə.mæn/)
        the Euro (/ðə.ˈjʊə.rəʊ/)
    And again, the weak or absent /h/ sound is slightly problematic because some will choose to pronounce
        the historical facts
    as /ðə.hɪ.ˈstɒ.rɪk.l̩.fækts/
    and some will prefer /ði.hɪ.ˈstɒ.rɪk.l̩.fækts/.
    The exception to this rule is when the article is stressed as in, for example:
        That is the tool for the job
    as /ðət.s.ˈði.tuːl.fə.ðə.dʒɒb/
    in which case it is marked to signal that it means the best, most appropriate or only tool for the job.  In written language, it is normally italicised or underlined in the marked form.
    In a range of languages which do not have a definite article (or any article system at all) the equivalent of the definite article is often a demonstrative determiner roughly translatable as this or that, these or those.
    In fact, the definite article in English shares an etymology with the demonstrative determiners and can be seen as a reduced form of them in Modern English.  In other words, this, that, these and those can be conceptualised as forms of the definite article marked for spatial relationships (near or far) and number (singular or plural).
  3. The proper article
    This is somewhat rare in English but occurs frequently in other languages leading some into error.
    For example, in Greek, Portuguese and Catalan, it is conventional to use an article before people's name (the Peter, the Maria etc.).  This also happens in informal use in German, French, Italian and Spanish.
    The proper article occurs less often in English but examples are:
        The Mr Jones I spoke to was very helpful
        The Strand is a road in London
        The Kremlin is in Moscow
        The Gambia is in Africa

    It is also possible for a/an to occur as a proper article although it is rare as in, for example:
        A Mrs Jones telephoned
    in which the speaker is signalling that the person is unknown except by name.
    Usage varies over time and countries once conventionally referred to with the proper article are no longer referred to that way so we have, e.g., Ukraine, not The Ukraine and Argentina not The Argentine.
    Modified country names conventional use the proper article:
        The United States
        The Soviet Union
        The United Arab Emirates

    In this guide, we consider proper articles in English as a subset of the definite article.
  4. The partitive article
    This only occurs in English with the determiner some as in, e.g.:
        Please give me some paper
        Pass me some pens

    However, other languages use the partitive article frequently and these include French, Greek, Italian and a range of others and in many of those languages they consist of a combination of the definite article with a preposition.  For example, in French, à + le = au and de + le = du.  In Italian, the preposition di combines with the definite article to produce dello, della and other forms equivalent to some or any in English and called a partitive article.  In Greek, the preposition se (at or in) combines with articles to form ston, sti and so on.
  5. The negative article
    In English, this role is taken by the word no which acts as a simple determiner.  However, other languages may reserve an article-like item for this function.  German, for example has the word kein which is inflected in the same way as the indefinite article to show gender and number.
    Fundamentally, English does not use a negative article but for those whose languages do, comparing no to the indefinite article has some validity.
  6. Zero article
    As the name implies, this is an absence of an obvious article and is usually represented as Ø.  Because English has a definite article denoting specificity as in, e.g.:
        Give me the money
    it also employs the zero article to denote an unspecified object before a count or mass noun as in:
        Give me money
        Take books with you

    The word some can be used as an indefinite plural article or to determine a mass noun as in, e.g.:
        Give me some money
        Take some books with you

    It is unhelpful to describe the lack of an article in languages which do not have an article system or those which have a reduced system as the zero article.
    It is also not the case that proper nouns in English usually take the zero article.  Most actually take no article at all so, for example:
        Peter is here
    is not an example of the use of the zero article because proper names do not normally take any article at all.  However:
        Rain fell overnight
    does contain an example of the zero article because that is often how we signal a mass noun non-specifically and should, if we are being strict be written as:
        Ø Rain fell overnight.
        The rain made the paths muddy
    which is the use of the definite article to refer to a specific mass noun.



In common with other function words, articles are subject to weakening in connected speech in particular.  This is what happens:

  1. Before vowel sounds:
    • The indefinite article, an, is reduced in rapid speech to /ən/ as in:
          an orange pronounced as /ən.ˈɒ.rɪndʒ/.
    • The definite article, the, retains a longer final sound as /ði/ (but is not as long as /ði:/) as in:
          the orange pronounced as /ði.ˈɒ.rɪndʒ/.
    • In both cases there is liaison so for example:
          an apple
      sounds more like a napple and there is an intrusive /j/ sound in
          the apple
      which can be transcribed as /ði.ˈjæp.l̩/, but not all speakers produce the intrusion and more careful speech usually avoids it.
      (Incidentally, the word apron in English was originally a napron but, by a process called misdivision it has become an apron.)
  2. Before /h/:
    As we saw above, /h/ is often pronounced very weakly so we get, e.g.:
    •     an historic moment
      pronounced as /ən.hɪ.ˈstɒ.rɪk.ˈməʊ.mənt/ with the pronunciation of the article reduced to /ən/.  In more careful speech, however, that might also be pronounced as /æn.hɪ.ˈstɒ.rɪk.ˈməʊ.mənt/ with the article in its full citation form.
      But when the /h/ is clearly sounded, we get, e.g.:
          a horrible experience
      in which the article is reduced to /ə/.
    •     the historic moment
      pronounced either as /ðə.hɪ.ˈstɒ.rɪk.ˈməʊ.mənt/ or /ði.hɪ.ˈstɒ.rɪk.ˈməʊ.mənt/ depending how careful the speaker is.
      In the case of a clear /h/ as in:
          the horrible experience
      the pronunciation remains as /ðə/ as in /ðə.ˈhɒ.rəb.l̩.ɪk.ˈspɪə.rɪəns/.
  3. Before other consonants such as at the beginning of sound, bag, cake etc.:
    • a is pronounced as /ə/ (/ə.ˈsaʊnd/, /ə.bæɡ/, /ə.keɪk/)
    • the is pronounced as /ðə/ (/ðə.ˈsaʊnd/, /ðə.bæɡ/, /ðə.keɪk/)


How do other languages work?

Languages differ dramatically in the use of articles (and some don't use them at all).  Here's a short list but you should rely on your own research into the language(s) of your learners.  Asking them is often useful as it alerts them to differences.

Languages with no article system
These include most Slavic languages (Russian, Polish, Bosnian, Czech etc.) as well as Chinese languages, Indonesian, Japanese, Hindi and Urdu.
For speakers of these languages, using the correct article in English is very challenging because they do not easily conceptualise the need to mark specificity and non-specificity or count vs. mass nouns.
Language with no indefinite article
These include most Celtic languages (Breton, Welsh, Gaelic, Irish etc.) and Turkish, Farsi and Arabic (which often encodes the definite article as a prefix).
Languages using affixation for articles
Some languages do not have a separate word class of articles but may use a similar system by adding suffixes to nouns.  These include Albanian, Macedonian, Bulgarian, Bengali, Romanian and Scandinavian languages.
Other languages such as Hebrew and Maltese use prefixes to denote an article system akin to English.

Many languages alter articles to show gender (most European languages) and it is impossible to use any noun, even an invented one, without first considering its gender.  European languages have two or three genders normally although more are possible.
Some languages, such as Basque, Georgian and most Native American languages distinguish between animate and inanimate nouns through the use of gender inflexions on the articles (and elsewhere).

Languages which are traditionally described as being article-less such as Japanese and Cantonese often use classifiers (sometimes called counters) to denote a wide range of properties in the nouns such as animacy, flatness, stick-like appearance and so on.  For more, see the guide to classifiers, partitives and group nouns, linked in the list of related guides at the end.


Three critical concepts

English has no gender marking on articles and we do not mark them for case or number either.
However, there is a deeply important distinction between three related concepts which determine how the article system functions:

  1. definite and indefinite: particular or general
  2. specific and non-specific (or generic): which or what
  3. mass and count: much or many

The three concepts are entirely lacking in many other languages.
Just as, for example, it is necessary to decide in some languages what the shape of object and what characteristics it exhibits before you can count them and in others what gender to ascribe to a noun before attaching a correct article as well as sometimes what case the noun is in, in English it is necessary to decide in terms of these three concepts before deciding which article is appropriate.

That is a serious conceptual challenge for many learners who, even at advanced levels, are unable to use the article system with consistent accuracy (or even consistent inaccuracy).
You cannot successfully teach the article system in English without making these three ideas clear.


The rules

The rules we follow arise from the three concepts we have identified.
We will refer here in all that follows to the distinction between indefinite but specific and definite and specific.  That's the key to have in mind.


Rule 1

Decide what you are talking about.  There are only three choices:

  1. One of some of many – indefinite but specific reference
    A man brought some flowers
    This means that the speaker / writer is referring to a specific class of nouns but not to the specific instance of the noun.  In other words, the noun is not identifiable by the reader / hearer other than knowing the class of nouns to which reference is being made.  The speaker / writer may or may not know more about the noun but this information is not being communicated to the hearer / reader.  Compare this to the third point, below.
    For example:
        A man arrived
        People arrived
        Information got lost
    In these examples, the hearer / reader only knows what sort of noun is in question (i.e., specific reference) but does not know any more about the noun (i.e., the reference is indefinite).
    The reference is specific but indefinite.
  2. All of them, everywhere – generic reference
    The wheel was an important invention
    This also means the speaker / writer is referring to a whole class of nouns, not a single instance of the class.  For example:
        A solicitor deals with legal matters
        The sundial was invented thousands of years ago
        Doctors charge a lot in my country
    In these examples, the speaker / writer is referring not to single instances of the nouns but to the whole class of nouns in general.
    The reference is, then, generic and indefinite.
  3. This one exactly – definite and specific reference
    The sun is our nearest star
    This means the speaker / writer is referring to a single, known instance of the noun.  For example:
        The man spoke to me.
        London lies on the Thames
        The wind is getting stronger
    Here, the reference is both definite (we know which noun is being referred to) and specific (we know what sort of noun is in question).  Normally, both the writer / speaker and the reader / hearer are aware of some or all of the noun's characteristics and can use that information to distinguish between instances of the noun in question.
    It will not, therefore, be surprising for you to discover that the definite article, the, is derived from the same source as the demonstrative determiners, this, that etc.
    The reference is definite and specific.
test If you want to, you can try a quick test to see if you have this rule clear.
Click here to do it.


Rule 2

Now we can start to select the right articles depending on what we are talking about.
In each of these categories, there's a choice of which article to use.

  1. If we are talking about indefinite but specific reference (one of many or some of many), we can have, e.g.,
        A man came in
        Ø Men came in
        Ø Good furniture is expensive
  2. If we are talking about generic reference (all of them or it, everywhere), we can have:
        A car is useful in the country
        Ø Cars pollute
        Ø Petrol is expensive
        The cat is an independent animal
  3. If we are talking about definite and specific reference (this one or amount exactly), we can have:
        The car is outside
        The sugar is in the cupboard
        The guests are here
        Ø Great Britain is an island
test If you want to, you can try a quick test to see if you have this second rule clear.
Click here to do it.

What are the choices of article in each category?

Here's the picture so far:

summary 1

We shall refine that diagram later.


Rule 3

It matters if the noun is countable or uncountable (i.e., a mass noun), singular or plural.
English is not unique but it does has a fundamental and very important distinction between mass and count nouns.  Languages which do not have this distinction (or in which the distinction is not grammatically significant) generally have much simpler article systems, or none at all.  It is almost impossible to use a noun correctly in English unless one has first considered whether it is being used as a mass noun or a count noun.

Fortunately, Rule 3 is quite simple:

  Count nouns Mass nouns
Singular the picture
a picture
the paint
Ø paint
Plural the pictures
Ø pictures
To put that table into words:
  1. Singular count nouns must be determined by a/an or the.  We allow:
        The parcel is here
        A parcel is here

    but not:
        *Parcel is here
  2. Plural count nouns must be determined by the or Ø.  We allow:
        The parcels are here
        Parcels are here

    but not
        *A parcels are here
  3. Mass nouns must be determined by the or Ø.  We allow:
        The packaging is expensive
        Packaging is expensive

    but not
        *A packaging is expensive

Now we can refine our rules by applying them to specific instances of the language.


Indefinite but specific reference (one of many)

write or think Here are three questions.  You will probably need a pen and a piece of paper to hand.
Make a note of the answers to the three questions and then click here for some comments.
  1. If you use indefinite but specific reference and want to talk about one of many uncountable (i.e., mass) nouns such as acid or furniture what article do you use?
    Fill these gaps with a(n), the or Ø:
    __________ tea contains as much __________ caffeine as __________ coffee
    I saw __________ rain had fallen
  2. If you use indefinite but specific reference and want to talk about one of many countable nouns such as houses or chairs, what article do you use?
    Fill these gaps with a(n), the or Ø:
    __________ room will be needed for the committee meeting.
    I saw __________ fox in the garden
  3. If you use indefinite but specific reference and want to talk about many countable nouns such as houses or chairs, what article do you use?
    Fill these gaps with a(n), the or Ø:
    __________ cars are expensive in my country
    We discovered __________ pollutants in the river water


Generic reference (all of them, everywhere)

write or think Here are three more questions.
Make a note of the answers and then click here for some comments.
  1. If you use generic reference and want to talk about all uncountable (mass) things such as money, love or water what article do you use?
    Fill these gaps with a(n), the or Ø:
    We all need __________ love
    We discovered __________ pollution in the water
  2. If you use generic reference and want to talk about all countable things in the plural such as houses or animals, what article do you use?
    Fill these gaps with a(n), the or Ø:
    __________ houses are expensive everywhere
    I enjoy watching __________ animals
  3. If you use generic reference and want to talk about one countable thing in the singular as representative of all such as unicorn or wheel, what article do you use?
    Fill these gaps with a(n), the or Ø:
    __________ train is usually cheaper than driving alone
    __________ smart phone has changed people's lives
    __________ dog is a faithful animal

The power of generic reference

People are sometimes confused about which article to use when expressing generic reference because it seems we can use all of them.  We allow, e.g.:
    A computer is a useful thing to have
    The computer has changed everyone's lives
    Ø Computers are getting cheaper
There is a reason for this.
Providing we do not use the Ø with a singular countable noun and reserve it for mass nouns as in:
    Ø Computer memory is now quite cheap
all other possibilities are open to us because the sense of generic reference to every instance of an item everywhere makes considerations of specific vs. non-specific reference and definite vs. indefinite reference irrelevant.  In other words, it overrides the necessity to think in those terms at all.

That is the reason we can say:
    Gorillas are powerful animals
    A gorilla is a powerful animal
    The gorilla is a powerful animal

with no difference in meaning.
All that remains is to consider ambiguity and style:


Definite and specific reference (this one exactly)

write or think Here are three last questions.
Make a note of the answers and then click here for some comments.
  1. If you use definite and specific reference and want to talk about one amount of a specific or particular uncountable (mass) thing such as acid or sugar what article do you use?
    Fill these gaps with a(n), the or Ø:
    __________ cardboard is in the garage
    __________ grass needs cutting
  2. If you use definite and specific reference and want to talk about more than one countable thing such as men or cars, what article do you use?
    Fill these gaps with a(n), the or Ø:
    __________ men you spoke to have decided
    The officer directed __________ bus drivers to their parking spaces
  3. If you use definite and specific reference and want to talk about one countable thing such as car or telephone, what article do you use?
    Fill these gaps with a(n), the or Ø:
    __________ car I bought was quite cheap
    __________ phone is ringing in the hallway
  4. If you use definite and specific reference and want to talk about one particular proper noun such as Berlin or Mary, what article do you use?
    Fill these gaps with a(n), the or Ø:
    __________ Napoleon was Emperor of France
    I gave the book to __________ Aunt Mary


The summary refined

Now we can refine the picture we had above to include the notion of (un)countability.

articles summary 2 


Articles in discourse

Articles have a discourse function and, as with much in connected discourse, a good deal depends on shared information.

Course books for learners will often have simplified (and often inaccurate) 'rules' for article use and we have set out the main ones above.  When these rules are apparently broken, the explanation often lies in the nature of the use of articles in discourse.
Consider these examples:

  1. A car arrived outside my door and the driver got out and walked up the path.
    1. If we follow the rule that the noun car here is specific but indefinite reference (i.e., it refers to one of many countable objects but the speaker and hearer both know what sort of object it is but not which one), then that happily explains the use of the indefinite article, a.
      However, the noun driver is also specific indefinite reference, isn't it?  We do not know which of the millions of drivers it is, just that it is one of them.  So, why the definite article which in the chart above is not an option because that applies to definite and specific reference?
      The answer lies in the shared information.  We know that only one driver is permitted per car and we also know which car is in question (it is the one which arrived) so we are, in fact, talking about definite and specific reference and the rule above is not broken.  It is:
          The driver of a car
      just as we can have
          The mane of a lion
          The teacher of a class
      and so on.
    2. This will also explain the use of the path because, again, the use of the definite article tells the hearer that the speaker has only one path from the car to the house (or, at least, that this path is only one that is relevant to what happened next).  If the sentence had been
          A car arrived and a driver got out and walked up a path
      then different messages will be sent:
      In this case it means that this driver was not actually driving the car at all but is a member of a class of drivers so it then becomes indefinite but specific reference (just as the article in a car is being used).  It also means that there were more than one paths and the person chose one of them, not a definite one from those available so that, too, is indefinite but specific reference.
  2. We chose a present for my brother but it was not a present he wanted
    Here, we have a present chosen from innumerable possibilities so the first article follows the rule: we are talking about a single specific but indefinite case so the indefinite article is valid.
    However, we then have a present again and this time it seems that the reference is definite and specific because we know what the present was (the one we chose).  Should it not, then, be the present?
    It could be, of course, but that would imply that he had other presents in mind that he did want (a definite and specific present) and the use of the article the would imply that.
    However, here, two things are happening:
    1. We have the dummy or existential it-clause in it was not a present he wanted so that serves to denote the definite nature of the present.  In other words, we know what we are talking about.
    2. We then have an indefinite article implying that from a large number of possible presents, this one was not wanted and that is indefinite but specific reference so the rules are not broken, it is the discourse intentions of the statement that leads to the article choice.  If we compare:
          He said he didn't want a gift like this
          He said he didn't want the gift
      the difference becomes plain.  The first is indefinite but specific reference and the second is definite and specific reference.
  3.     A cat can be good company for lonely people
        A cat is an independent animal
        Cats are independent animals
        The domestic cat is descended from wild animals in the Middle East

    If these are all examples of generic reference to countable nouns, why the difference?
    Partly, as was said above, this is a stylistic issue.
    The use of the indefinite article to refer to a generic case of a countable noun requires the use of the singular form.  It is generally considered to be stylistically rarer and more formal.
    The form of choice is usually the plural as in the third example but the second example is common enough.
    In the first example, we have a grey area because it may be assumed that the speaker is referring to indefinite but specific reference (on the left of the diagram above) and suggesting that lonely people should acquire a cat (any cat) for company rather than suggesting that all cats are suitable as company for all lonely people.  In this case, however, the speaker probably has a singular cat (rather than lots) in mind and so uses the indefinite article in the way that many other languages would use a numeral.  (In French, for example, that would be un chat, in German eine Katze, in Spanish un gato and so on for many other languages in which the indefinite article shares the same form with the numeral 1.)
    The final example, too, verges on definite reference (on the right of the diagram) because of the use of the classifier domestic.  Classifiers often have the function of moving the generic to the definite and specific in terms of reference so the use of the definite article is appropriate and the rule is not broken.


The overarching phenomenon that the examples in this section exhibit is cohesion.  Article use contributes powerfully to textual cohesion (written and spoken) by signalling to the reader / hearer that the reference is to a known item or an instance signalling the only possible entity in context (as in the fact that cars only have one driver each).
The definite article may also, as we saw, refer to something outside the text which is known to both speaker / writer and reader / hearer because they share a common cultural or social milieu.  For example,
    The minister has replied to our letter
Now, minister can mean a politician or a member of the clergy and there are many thousands of them around the world.  It is clear, however, from the use of the definite article that a particular minister, known to both participants in the discourse, is meant here.
Another example, of what is called homophoric reference is to entities such as the government, the countryside, the north, the Queen, the President, the Czar etc. when knowledge of the culture and national context precludes any other meaning.


So-called quirks and so-called exceptions

The English article system is often wrongly presented as an impossibly difficult area.  As we saw, however, the rules are quite simple.  There are, however, a few quirks concerned with the use of the definite article.
There are exceptions to grammatical rules in a number of areas of the grammar of all languages as anyone who has tried to learn a second or additional language knows only too well.
However, labelling a phenomenon as an exception is sometimes the resort of people who have failed to analyse it properly.

So-called exceptions with the

These can all be traced back to the rules above.  We will note the rule in bold.
These aren't lesson topics – they should be taught as and when they arise.

  1. One teachable case of definite and specific reference (this one exactly) is when the noun has been mentioned or it can be assumed that a unique reference is intended and understood.
    So we get, e.g.
        A car drove by and the driver waved
        The toilet's probably upstairs
    This is often referred to as the unknown-known rule and can easily be explained that way.  The rule, so called, is actually just another way of referring to a definite and specific item or person and that is simply following the rules.
    An explanation of a sentence such as:
        She bought a new car.  The car broke down on her first journey.
    does not require the invocation of a new rule and is:
    1. in the first instance, we are referring to an indefinite but specific reference for a countable noun and that, as we saw, requires the indefinite article.
    2. in the second instance, we are now referring to a definite and specific reference for a countable noun (because we now know that the car was hers) and that requires the use of the definite article.
    We do not need to invoke a special known-unknown rule to explain this.
  2. When a noun is modified, it's also a sign of definite and specific reference and that requires the definite article again.
    So we get, e.g.
        The man who is married to the Minister
        The author of this guide
        The girl in the corner
    Modification takes many forms:
    1. Modification of country names
      Country names which are modified by an adjective such as United, Islamic, Peoples' or Federal require the definite article because we need to follow the definite and specific reference rule
          The United States
          The Federal Republic of Germany
          The United Arab Emirates
      In other words we are using definite and specific reference and the use of the definite article is following the rule.
      Otherwise, nations and languages take no article as we would expect because proper nouns do not take articles.
    2. Modification by name or topic
      We would expect words such as theory, law and effect to be indefinite but specific references to types of ideas so we get, e.g.:
          That a good theory
          It's a new law
          What an interesting effect!

      When we modify the words, we need definite and specific reference so we shouldn't be surprised to find the use of the definite article as in, e.g.:
          The Doppler Effect
          The Theory of Relativity
          Hook's Law
      etc. all of which are acting as modifiers of the second nouns so the rule is obeyed for definite and specific reference.
      When the possessive 's is used there is no article: Einstein's Theory, Murphy's Law and that follows the rule of not using an article with proper nouns, of course.
    3. Modification by inflexion or most
      Superlative forms are by their nature unique and defined so we should not be surprised that we follow the rule for definite and specific reference and have
          the biggest building
          the oldest man
          the most difficult question
      On the other hand, comparative forms are not unique so we follow the rules again and arrive at:
          a bigger problem
          a brighter light
          a more interesting idea

      etc. and that follows the rules for indefinite but specific reference.
      However, if only two items are being compared, then we are signalling that one of them is unique and that requires the definite article rule so we get:
          the better wine of the two
          the more expensive choice of the two
    4. Omission of the modifier
      Geographical areas can be explained by noting that the unique identifying modifier has been omitted:
          The Atlantic (Ocean)
          The (River) Amazon
          The Tate (Gallery)
          The Alps (Range)
          The Hilton (Hotel)
      All of these follow the rule for definite and specific reference
      although the reference is ellipted.
  3. Unique objects (or objects unique in a certain shared setting):
        the sun
        the moon
        the Milky Way
        the Queen
        the President
    etc. are all instances of definite and specific reference so no rule is broken.
  4. Nationalities are definite and specific reference to plural concepts so the definite article is required:
        the Greeks
        the French
        the Spanish
    etc. and no rule is broken.
  5. Plural countries always take the article:
        The Netherlands
        The Bahamas
        The Seychelles
    etc. and that follows the rule of definite and specific reference to a plural count noun.
  6. Families count as plural definite and specific reference:
        Take tea with the Windsors
  7. Rivers always take the definite article the, even if they aren't unique because they are definite and specific reference:
        The Stour
        The Thames
        The Nile
    In the first case here, there are, in Britain, at least five rivers called The Stour but the use of the definite article makes it plain that we are talking about a local instance of such a river so no rule is being broken.
  8. Lakes are also proper nouns so having no article is following the rule for them.  When they are modified and made unique in that way, we follow the rules and use the definite article as in
        Lake Chad
        Lake Victoria
        Loch Ness
        Lake Windemere
        The Great Lakes
    If we ellipt the qualifier Lake, we maintain the rule that proper nouns take no article:

So-called exceptions with Ø

It has been pointed out that the use of a singular count noun without an article is not usually allowed in English so we do not encounter, e.g.:
    *Person is at the door
    *Letter has been opened

Furthermore, we distinguish between indefinite but specific reference by using a(n) and definite and specific reference with the.
That should all be clear by now.

The following three areas are, therefore, often despairingly labelled 'exceptions' in course books and grammars for learners.

  1. Some common prepositional phrases often with verbs like go, have, get, take, eat, and be involve indefinite but specific reference:
        go by bus
        be in school / church / prison / hospital
        go to university
        eat breakfast
        have lunch
        have appendicitis
        get flu
        travel by air
        go to college
    The nouns are nearly always means of transport, meals, illnesses or institutions.
  2. Parallel structures take Ø:
        hand in hand
        man to man
        man and boy
        pen in hand
  3. Times with the prepositions at, by, after, before take the zero article but those following during and in take the:
        at dawn / sunset / night
        by dusk / sunrise / evening
        after dark
        before nightfall
        during the day
        in the morning

There is, however, a rule-based explanation for these so-called exceptions.  In all these cases the count nouns are being used not for reference to a singular or plural entity (that's why it is on foot, not on feet, by bus not by buses etc.).  The count nouns are being used as representatives of the abstract idea of something (i.e. a mass concept) rather than an incidence of something identifiable.  That is why we can say, for example:
    University is not for him, I suspect
because the noun is being used to describe university education rather than having any specific reference at all.
The same considerations apply to other examples in the list.
    to be in school
refers to being in education
    to go on foot
refers to a type of mobility
    to go by bus
refers to a type of transport
    after nightfall
refers to the absence of light
    arm in arm
refers to a type of association
and so on.
We can usually come up with a mass noun to express the concepts and that is indicative of the fact that we are dealing with a mass concept so we should not be surprised that the zero article is being used.  That is simply following the rules.
When the Ø article is used with time expressions, the same abstraction of the time to a mass concept accounts for the use.  The expressions:
    at night
    by day
    in autumn

etc. are slightly quirky prepositional uses but the article use is not.

When the definite article is being used with time expressions, we are often referring to generic reference so:
    I like to work during the night
refers to all nights, not a specific night.
    He can't get out of bed in the morning
refers to all mornings, not a particular one.
This may be a slightly unusual use of a generic structure with the definite article but it follows the rule.

There are a couple of exercises for more advanced learners on article use in the section for learners on this site.  Go to that index, find the exercises and see if you can identify which rules from all of this are applicable (new tab).

Click to take a test in this area.

Related guides
classifiers, partitives and group nouns for the guide to a related area which considers, inter alia, one way mass nouns are made countable
lesson for elementary learners which focuses on the for unique use, some for mass nouns and plural count nouns and the known-unknown rule for using a(n) and the
this guide this is an abbreviated version as a PDF document
teaching the system If you are happy that you have understood the nature of the article system in English
mass and count nouns this is an essential guide in the initial-plus section
nouns the guide in the in-service section