Hindus believe in one God-- the omnipotent, omniscient. They also believe in Karma- actions and hence, in reincarnation. What you sow, so shall you reap. There are no hard and fast rules. You can...
Hindus
The name of a person/people that believe in Hinduism is Hindu(s).
For the same reasons people practice any other religion. They have been taught to believe it is the correct set of tenets to follow.
roughly 900 million to 1 billion though some say 1.5 billion