Hinduism, with about one billion followers is the world's third largest religion, after Christianity and Islam. However, it is not a religion of the same kind as the other two main religions. Hinduism is a very old religion from India that is still practiced today. It was one of the first religions that had the idea of reincarnation (that people can be born again after death), karma (one event invents another, or that every action has its consequences), and other ideas.

Hinduism is not simple. Hinduism has been described as a tradition having a "complex, organic, multileveled and sometimes internally inconsistent nature". Hinduism does not have a "unified system of belief encoded in a declaration of faith or a creed", but is rather an umbrella term comprising the plurality of religious phenomena of India.