What happens in the afterlife depends on which religion you follow, however most modern religions say that there is some form of judgement in which the fate of the soul is determined.
Christians, Jews, Muslims and Zoroastrians say that the souls of believers will go to heaven or paradise, although in most cases this may depend on the sins the person committed on earth. Catholics believe that believers who have committed minor (venial) sins, that have not been forgiven, will spend some time in a purgatory, a place of temporary punishment; they also believe that the souls of unbaptised babies go to limbo, although the Church appears to be moving away from this doctrine. In heaven, souls can live in comfort and joy, and in the eternal company of God. Muslims also believe that those who take part in jihad go straight to heaven, without further judgement, and are met by eternal virgins. Those who are judged unworthy of heaven go to hell. This is typically thought of as a place of fire and eternal punishment.
Daoists and some Buddhists believe that the soul is reincarnated as a new person, in a never-ending cycle, until perfect knowledge and righteousness is achieved. The soul then goes to heaven and joins the gods.
Atheists believe there is no afterlife.