Reincarnation
The Hindus believed that the soul went through a series of rebirths, as it strived to obtain a oneness with the universal spirit, or Brahman Nerguna. They believed that when a person died, they would be reborn again, living many lives, until they perfected themselves. This state of perfection was called moksha.
They believed that how a person lived their current life would determine the form they would take in the next life. If they lived a good life, and fulfilled all their dharmas or duties, they might be born into a higher varna or class in the next life. If they lived poorly, they might be born into a lower life, or even into a lower life form, such as a beetle, or snake.
When one obtained this state of Moksha their cycle of rebirth after rebirth would finally stop, and they would live in eternal happiness at oneness with the Brahman Nerguna.