Most Hindus believe that humans are in a cycle of death and rebirth called samsara. When a person dies, their atman (soul) is reborn in a different body.
Some believe rebirth happens directly at death, others believe that an atman may exist in other realms. Hindus believe that an atman may enter swarg (Hindu heavenly realm) or narak (Hindu hellish realm) for a period before rebirth.
Hindus believe in karma. Many believe that good or bad actions in life - leading to positive or negative merit - determine the atman’s rebirth.
Some Hindus believe that humans may be reborn in animal form, and that rebirth from human to animal form only occurs if an atman has repeatedly failed to learn lessons in human form.
Living life according to teachings in the scriptures will eventually lead to moksha. Some Hindu scriptures describe moksha as the atman becoming absorbed with Brahman, from where each atman is believed to originate. Other Hindu scriptures describe moksha as living in the realm of a personal God. The Maitri Upanishad (sacred text) states the following:
Even as water becomes one with water, fire with fire, and air with air, so the atman becomes one with the Infinite Atman (Brahman) and thus attains final freedom.Maitri Upanishad 6.24