There is a subtle difference. "Somebody" implies a kind of specificity - i.e. "some body" or "some person". "Somebody did this" would mean "some (specific) person did this", but "anybody did this" does not make grammatical sense. Anybody implies a lack of specificity. You could say "anybody could have done this" and it means "it is unknown which person did this". "Somebody could have done this" means "it is possible for a person to have done this". There are indeed many usages where "somebody" can be used in place of "anybody" (or vice versa) but the meaning may change slightly. Try substituting the words "some person" or "any person" in your sentence, and that will help you decide whether to use "somebody" or "anybody". =cjs

"somebody" is more reffering to one person, and "anybody" is reffering to either" a group of people or one person" example.(anyone want to chat with me?), and( somebody has a crush on you)