Articles

A, An and The are known as Articles.
Articles are of two types. 
A] Indefinite Article: a, an.
1) Which is used before indefinite person or thing.
(A teacher: that is any teacher)
2) It is used before singular countable noun.
(A pen, a book, a cat etc.)

Use of ‘An’
1)An is used before the singular word beginning with a ‘vowel’ (a, e, i, o, u) sound.
(An enemy, an ant, an orange)
2) An is used before a word of which sound is of vowel if it starts with ‘h’
(An hour, an honest, an heir)
3) An is used before short forms:
(An M.A., an M. Com., an SP, an MP)
4) Before an adjective begins with vowel sound.
(an old woman/ an inspiring story.)

Uses of ‘A’
1)A is used before the singular word beginning with consonant.
(A pen, a car, a class)
2) A is used before a noun beginning with vowel but the sound is of consonant.
(A European, A University, a one eyed man, a unity)
3) Before an adjective begins with consonant
(a beautiful garden, a nice suggestion)

Definite Article “The”
The is used before particular person or thing (we know it)
1) He saw the teacher (particular teacher)
2) The is used before singular countable, plural countable and uncountable noun.
(The pen, the boy, the books,)
3) Used when a singular noun represents a whole class/group.
(The dogs is an honest animal, the rich should help the poor,
The rose is a lovely flower.)
4) Used before name of things unique of their kind
(The sun, the moon, the sky, the Earth)
5) Used before the ordinals (number)
(The first, the second, the third)
6) used before the word ‘same’ (the same boot, the same house)
7) Before the name of newspaper magazines, holy books,
-The times of India, the Lokmat times, the Hindu, the bible, the Vedas, the Mahabharata, the Ramayana, the twinkle,
8) Musical Instruments: The violin, the flute, the piano,
9) Superlative adjective: -The best, the most beautiful, the tallest
10) Historical events: (Day)
-The Republic day, the Independence Day, the mother’s day.
11) Historical buildings or directions (sides):
-The Tajmahal, The red fort, The East, The north, The right side, The left side)
12) Names of Oceans, seas, rivers, desert, canals, group of islands, mountains.
-The Indian Ocean, the Arabic sea, the Sahara, the Panama Canal, the Ganga, the Andmans and the Nicobars.
13) Before the proper noun when it is compared to other.
- Tukaram Maharaj is the Shakespeare of Maharashtra.
14) When the same nouns are repeated, use ‘a/an’ before the first noun and ‘the’ before the second noun.
-I saw a book. The book is very interesting.
15) Plural name of a country.
The USA, The USSR.