don't you have chapter of articles.

An article is a word that is used for indicating whether a noun is specific or non-specific. In other words, when an article is present before a noun, it shows whether that noun is some general noun or some particular noun.

There are two types of articles—the indefinite article ‘a’ or ‘an’, and the definite article ‘the’. The first type points out non-specific or general nouns and the second type points out specific or particular nouns.

For example:

A boy

(Here, the presence of ‘a’ shows that some general/non-specific ‘boy’ is being talked about.)

An elephant

(Here, the presence of ‘an’ shows that some general/non-specific ‘elephant’ is being talked about.)

The red car

(Here, the presence of ‘the’ shows that some particular/specific ‘red car’ is being talked about.)