What happens after death? We won't try to give an answer (even if we had one) here. But if you're interested in exploring this question, you're interested in eschatology — the part of theology that has to do with death or the end of the world.
Eschatology comes from the Greek eskhatos, meaning "last," which makes sense given that this branch of theology is preoccupied with the study of the last part of life or death. More specifically, eschatology involves four elements or "last" things: death, judgment, heaven and hell. It's an examination of the ultimate destiny of mankind.