Usage of articles A, An, and The | English Grammar

indefinite articles	A, An
definite article	The

lets say if you want to elaborate about anything which is general or Any normal object then you should use indefinite articles or A, An. but if you want to mention something which is specific or static thing then you should use Definite article "The".

For an example,

Purvi wants to study English grammar from a website.

well website is not a specific or any kind of static thing or object to be mentioned as a "the" articles but lets say if purvi has a static object.

Purvi wants to study English grammar from the postalassistantexam.blogspot.in

How to use Articles in English grammar 

A, is used on consonant sound, 

on before singular countable nouns.

An, is used on Vowel Sound, 

on before singular countable nouns.

see these examples 

A

A book

A shell

A shirt

A cat

An

An elephant

An umbrella

An article

Tricks to remember

Articles are all about sounds not letters, one does not simply to consider letters while putting articles before noun. let's say A,E,I,O,U letters sounds like we can put "An" before any noun spell which can starts from it?

like : 

I am writing this article for a hour