Immortality or eternal life is the idea of something which is alive that will stay alive forever. The opposite of immortality is mortality, which means a living thing can die. Right now, only a small number of living things are known to be immortal. These are mainly simple, lower forms of life like bacteria. Stories about immortal people or animals are popular in fiction and mythology, but not yet actually possible. Many religions say people have an immortal soul with an afterlife.