Using Articles A, AN and THE

Introduction : 
    The correct use of the article (a/an/the) is one of the most difficult points in English grammar. Fortunately, most mistakes do not matter too much even if we leave all the articles out of a sentence.

Most of western European languages have article system very like English.

A / An

* We use a/an with a noun to talk about just one number of that class (A/an means one).

example : 

She lives in a nice big house

My father is an engineer (NOT: My father is a engineer) 

Tanaka is a Japanese name.

A girl phoned this morning.

* We use a/an when we define or describe people or things (when we say what class of kind they belong to)

example: 

He's a doctor.She's a beautiful woman.

It's a calculator.

* We do not use a/an with plural or uncountable noun because a/an means one.

example:

My parents are doctors. (NOT: My parents are a doctors)

Would you take some salt? (NOT: Would you take a salt?)

* We do not use a/an with an adjective alone (without a noun) example:
She's a very good engineer 
She's very good. (NOT: She's a very good)

* We do not use a/an to gather with another determiner (for example my, your)
examples:
He's a friend of mine (NOT: He's is a my friend)
She's writing another drama (NOT: She's writing an other drama)

The 

The means something like 'you know which one i mean.' It is used with uncountable, singular and plural nouns 
Examples:
The water (uncountable noun)
The table (Singular)
The Stairs (Plural)

* We use the to talk about people and things that we have already mentioned.
example: 
She's got two children; a girl and a boy; The boy's fourteen and the girl's eight.
* When we are saying which people or things we mean.
example:
Who's the girl is the car over there with John?
* When it is clear from the situation which people or things we mean.
example:
Could you close the door? (only one door is open)
Could you pass the salt.
'Where;s ann?' 'In the kitchen.'
* We do not use the with other determiners.
(for example my, this, some)
Examples:
This is my uncle. (NOT: This is the my uncle.)
I like this beer. (NOT: I like the this beer.)
* We do not usually use the with proper nouns (there are some exceptions we see forward)
example:
Mary lives in Switzerland. (NOT: Mary lives in the Switzerland) 
* We do not useually use the to talk about things in general.
example: 
Books are expensive. (NOT: The books are expensive.)

[NOTE: For the pronunciation of the will be listed forward]

Click here to know the different between A,An and The