They introduce a dependent (subordinate) clause, which gives more information: who, whom, which, that.

(a)  

They are used for non-specific items and people: anyone, someone, all, both, few, each...

(a)  

These begin questions: Who, Which, What, Where, How

(a)  

These are used to show ownership: my, your, his, our, hers...

(a)  

They refer to another noun in the sentence and end in -self or -selves: himself, herself, yourself

(a)  

They are used to add more emphasis to a subject and end in -self or -selves: myself, himself, herself

(a)  

They are used as substitutes for a noun or pronoun in a sentence: he, she, I, me, we, it...

(a)  

representing only one

(a)  

refers to more than one person or thing

(a)