Indefinite pronouns are those referring to one or more unspecified objects, beings, or places. They are called "indefinite" simply because they do not indicate the exact object, being, or place to which they refer.
Indefinite pronouns include partitives such as any, anybody, anyone, either, neither, nobody, no, someone, and some; they also include universals such as every, all, both, and each; finally, they include quantifiers including any, some, several, enough, many, and much. Many indefinite pronouns can also function as determiners.
There are just two important rules for using indefinite pronouns correctly. Remember these and you will find that writing comes easier for you.
In the following examples, the indefinite pronouns are italicized.
Many are called, but few are chosen.
Somebody ate my sandwich!
Everyone says she is beautiful inside and out.
No one wants to hear about my health problems.
Either choice has its advantages.