Heaven is the sky. The word heaven comes from the old English word for the sky and the prevailing belief among most religions was that the gods lived in the sky. Christians and muslims are more or less the religions that teach that the sky can also be an afterlife for humans, but in most ancient religions, the gods and mortals are ALWAYS separate. Mortals live on earth and at death they are sent to the afterlife (Roman elysium, Greek hades, Hebrew sheol, etc.) They never dwell with the gods unless the gods make an exception. That being said, in the Christian and Islamic afterlives, pious believers are rewarded by being granted an eternal dwelling place in heaven (the literal sky) with God.
According to Buddhism you can be reborn in heaven. Just not eternally. Once the good karma that got you there has been used up, you start again at the bottom. Buddhism teaches that there are six possible destinations after death; hell, ghost realm, animal realm, human, demigod, heaven. Beings keep cycling through these options till they've had enough and try to reach nirvana. Not sure about Hinduism, but probably something similar.