Polytheism is belief in many gods — it's kind of the opposite of monotheism, which is belief in one god. If you believe in polytheism, you have a bunch of gods to thank or blame.
Though the most widely known religions today — Christianity, Judaism, and Islam — are all examples of monotheism, there have been plenty of religions that preach polytheism. Followers of those religions believe in a pantheon or group of gods, like the ancient Greeks who worshipped Zeus, Athena and the gang. Usually in polytheist religions certain gods are associated with specific things, like war or love.
