Rules of Using Articles

There are two types articles in English language.

1. Indefinite article: a/an
2. Definite article: the

An article is used before a noun or an adjective modifying a noun. 

Definite Article 'The'

The definite article "the" is used for a definite, specific or particular noun.
   e.g.  Mr. Roy bought the car.
The article “the” before the noun “car” in above sentence means that the car, Mr. Roy bought, is a specific or particular car and not any car.

                          Indefinite Article 'A' and 'An'

The definite article “a/an” is used for indefinite, non-specific or non-particular (common) noun.

   e.g.  Mr. Roy bought a car.

The article “a” before car in above sentence means that the car he bought is any car and not a specific or particular car.

Rules for using Indefinite Article ‘A’

1.The article indefinite “a” is used before a word (singular noun) which begins with a consonant.

   e.g.  a book, a cat, a camera, a dog etc.

2. Before a word which begins with a vowel having the sound of ‘yu’.

   e.g.  a unit, a uniform, a European, a university etc.

3. Before a word which begins with ‘O’ that sounds as ‘wa’.

   e.g.  a one-eyed deer, a one-rupee note, a one-day cricket match etc.

4. As preposition to mean ‘per’ or ‘each’.

   e.g.  He earns ten thousand rupees per month ( a month = per month). He takes tea three times a day ( a day = each day).

5. Before a singular noun which refers to a class of things.
    e.g.  An orange is rich in vitamins.

6. Before a name of a profession
    e.g. He wants to be a teacher. She is an engineer.

7. For certain expressions of quantity.
    e.g. a lot of, a few, a couple, a dozen etc.

8. For certain numbers.
    e.g. a hundred, a thousand, a million etc.

9. To indicate a sense of ‘one like’.

    e.g. He thinks he is a Newton.

10. After ‘what’ in exclamatory sentences beginning with ‘what’.
    e.g. What a beautiful flower!
           What a nice shirt!

11. To indicate ‘whole class’.

    e.g.  A cow is a domestic animal.

N.B. : Definite article ‘the’ is also used to indicate such a ‘whole class’.

    e.g.  A cow/ The cow gives us milk.

12. To indicate any ‘unknown name’ or ‘surname’.

    e.g.  A Amal Dutta was present there.

13. Before the superlative ‘most’ when it means ‘very’.

    e.g.  He saw a most wonderful sight. (a most = a very)

14. Article a/an is not used before uncountable nouns
    e.g. water, milk, sand etc.

Rules for using Indefinite Article ‘An’

1.Before a word  beginning with a vowel (a, e, i, o, u)

    e.g.  an apple, an egg, an owl, an umbrella etc.

2. Before a word beginning with a consonant having vowel sound.

    e.g.  an M.A., an M.P., an M.L.A., an M.B.B.S. an S.D.O., an F.I.R. etc.

3. Before a word beginning with silent ‘h’.
    e.g.   an hour, an honest boy, an honourable judge etc.

Rules for using definite Article 'The'

1. To refer a thing or event of  which only one exists in nature.
    e.g. the earth, the moon, the sky,  the north pole, the equator.

2. For a noun which becomes definite or particular because it is already mentioned and is being mentioned a second time.
    e.g. The teacher helped a student and the student became happy.

3. For a noun made specific or definite in a clause or a phrase.
    e.g. The old lady, The girl with blue eyes, The boy that I saw, The nice red shirt

4. Before superlative degree of adjective .
    e.g. He is the best boy in the class. He is the most wanted person.

5. Before a phrase composed of a proper and common noun
    e.g. The New York city, The river Nile, The library of Congress

6. Before the names of organizations
    e.g. The Association of Chartered Accountants, The World Health Organization

7. Before names of scientific principles, theories, laws etc.

    e.g. the Pythagorean Theorem, the laws of Newton, The Fahrenheit Scale.

N.B. : But no article will be used for these names if written in forms like, Newton’s Law, Dalton’s Law of Partial Pressures, Hook’s Law of Elasticity.

8. Article “the” is not used for names of universities if written in forms like Oxford University, Yale University, Columbia University. But article “the” is used if names of university are written in forms like The University of Oxford, The University of Yale, The University of Toronto.  

9. Before the names of rivers, seas, oceans, islands, desert, mountain ranges, famous buildings, religious communities, holy books, newspapers etc.

   e.g.   The Bay of Bengal, The Ganges, The Indian Ocean, The Andamans, The Sahara, The Himalayas, The Taj Mahal, The Hindus, The Muslims, The Gita, The Bible, The Koran, The Statesman, The Anandabazar etc.

10. Before a Proper noun used as Common noun for comparison.

   e.g.  Kalidas is the Shakespeare of India. Ahmadabad is the Manchester of India.

11. Before the ordinal numbers of nouns, dates etc.

   e.g.  The first boy, the second bench, the 23^rd January.

12. Before the abbreviated and full name of countries which are collectively formed.

   e.g.  The U.S.A. / the United States of America, the U.K. / the United Kingdom.

13. Before the name of important historical events.

   e.g.  The Sepoy Mutiny, The First World War, The French Revolution.

14. Before the name of a nation or race.

  e.g.  The Bengalees, The English, The French.

15. Before the names of musical instruments.

   e.g.   the flute, the guitar, the piano, the juzz etc.