- Any one of all things. You use this when there is no limit to what might be meant. You might be able to change "anything" to any other word.
- I'll do anything you want.
- Is there anything he has not done?
- I don't have anything left.
- Anything is not like a usual pronouns. It has no reflexive form and no different subject or object forms. It even uses the possessive 's of common nouns. For this reason, some people consider it to be a compound determiner.