The Articles

A or an and The are called articles.
Use of A _ used before singular countable nouns.
Example  a book, a girl
* If a word started from vowal but sounds consonant therefore article A will be used.
Example. A university, a European
Use of An _ used before singular countable nouns that started from vowal ( a,e,I,o,u) or vowal sounds ( y, ) .
Example an orange, an owl, an elephant, an electronic wire.
*In some word if sound is vowal but Word is started from intial consonant H therefore article An will be used.
Example an hour, an honest man.
Use of The_ 1 used before singular and plural countable nouns and uncountable nouns.
Example
The book, The books, The milk.
2  When talk about a particular person or thing.
Example The girl cried.( About a particular girl)
3 if a singular nouns represent a whole class.
Example
The cow is useful animal.
The horse is a noble animal.
The rose is sweetest of all flowers.
4 Before some proper names –
* Oceans and seas – The Pacific , The black sea
* River – The Ganga
*Canals- The Indira Gandhi Nahar
* Desert – The Sahara
* Group of island- The west Indies
* Mountain range- The Himalayas
* Name of some countries that includes word republic and kingdom – The United kingdom, The Irish republic.
* Also some countries- The Ukraine, The Netherlands
5 Before the name of certain books- The Vedas, The puranas, The Illiad, The Ramayana
But no article will use if we say Valmiki’ s Ramayana or Homar’ s Iliad
6 Before the unique things- The sun, The sky , The Earth.
7 Before a proper noun when an adjective come before a proper noun.
The great Shakespeare.
8 With superlative degrees – The darkest cloud, The Best book
9 Before the ordinal or numbers – First Indian
10 Before the musical instruments- He is interested to play the flute.
11 When an adjective using as the noun.- The poor are always with us.
12 When an adverb with comparative degree- The more they get.
Ommision of the article
1 Before the name of substance and uncountable nouns if used in general sense.
Example
Sugar is bad for your teeth.
Wisdom is the gift of heaven.
But if substance and uncountable nouns used in particular sense then article  The will used .
Example
Would you pass me the sugar?( here sugar is particular kept on the table therefore there is no general sense but particularly about the sugar that is kept on the table.)
Example
The wisdom of Birbal is great.( Here we are talking about the wisdom of Birbal which is about a particular person.)
2 Before plural countable nouns used in general sense.
Example
Children like chocolate.
3 Before most proper nouns , names of people, continents, countries, cities, individual mountain, individual island,clakes, hills etc.
4 Before names of meal used in general sense.
Example
What time do you have lunch?
Dinner is ready.
But if we have an adjective before the name of meal then we use article.
Example
I had a late lunch.
The dinner we had at hotel golden is good.
5 Before languages
Example
We study French.
6 Before school, college, university, church, bed, hospital, prison, when these places are visited or  thieused for primary purpose.
7 Before names of relations-
Example
Father, mother, uncle,aunt,nurse,cook
Repetition of the articles
1 When two or more adjectives attached to the same noun, article is used before the first adjective only but when an adjective attached to different nouns than article is used before the each adjective.
Example
I have a black and white dog.
I have a black and a white dog.
In sentence 1 only one dog is described that is black and white in his color therefore only one time article A is used here but in sentence 2 there are two dogs ,one is black and other is white so here article A is used more than one time before the each adjective.
2 If two nouns refer to the same person or thing ,the article is used before the first noun only.
Example
He is a better machnic than clerk.