Anybody means any person at all, without specifying who. When you say “Can anybody help me carry these books?”, you're asking if any person is available, not looking for someone specific.

The word works in questions, negative statements, and conditional sentences. You might wonder if anybody remembered to bring snacks, or announce that you didn't tell anybody your secret. If your teacher says “Anybody who finishes early can read quietly,” she means any student who finishes, whoever that turns out to be.

Anybody differs slightly from anyone. They mean the same thing, but anybody sounds more casual and conversational, while anyone fits better in formal writing. You'd probably say “Is anybody home?” when you walk through your front door, but write “Anyone interested should sign up” on a club poster.

The word suggests openness and possibility. When a contest announces that anybody can enter, it means no one is excluded. When someone says “Anybody could have made that mistake,” they're recognizing that the error was understandable and human. The beauty of anybody is that it includes everyone equally, without favoring or excluding a single person.