ARTICLES IN SENTENCES

There are two articles : A ( or An ) and The
A or An is called the Indefinite Article and The is called Definite Article.
Use of the Definite Article
The Definite Article " THE " is used
1. When we speak of a particular person or thing,or one already referred to :as
-The book you lent me is very interesting.
2. When a singular noun is meant to represent a whole class,as
-The rose is the sweetest of all flowers
3.With names of gulfs,rivers,sea,oceans,group of islands and mountain-ranges;as
-The persian Gulf
-The Read Sea
-The British Isles
4. Before the names of certain book;as
-The Ramayana
5.Before common nouns which are names of things unique of their kind;as
-The sun, The earth,etc
6. Before a Proper noun only when it is qualified by an adjective;as,
-The great Caesar
7. With superlatives;as
-This is the best book of English Grammer
8. With ordinals;as
-The second section of this book is difficul to understand
9. Before musical instruments;as
-He played the guitar very beautifully.
10. Before an adjectife when the noun is understood;as
-The rich should help the poor.