Non-Assertive Indefinite Pronouns and Determiners

used to refer to an unspecified quantity or number, especially in questions or negatives

I don't have any idea what he's talking about.

used for referring to a person when who that person is does not matter

Is anyone available to help with the project?

used to refer to any person, without specifying who or what kind

Is there anybody who can help me with this?

used for referring to a thing when it is not important what that thing is

I don't have anything to wear for the party.