This question has been asked morethan a million tines. Christianity and Islam, the two major religions have without any doubt assured humans of life after death, which will begin with God's verdict on individual souls, also referred to as judgment day. Hence, all souls will be sentenced to either heaven or hell depending on their earthly deeds. It is only right we choose heaven or hell to as the destination of afterlife.
However, not all humans are Christians or Muslims who believe in heaven or hell. This is when uncertainty comes to play as many other minor religions have different narratives on life after death. Vikings for instance believes in Valhalla, an un-earthly heaven like place, where warriors will be brought in by valkaries to live amongst gods for eternity.
Science can not be left out on this topic, it qualifies as system of belief in someway. I think the religion of science is called Scientology. Even without mentioning Scientology, science has made believers out of every other religion with over half of the world using it's instruments. But unfortunately, science is yet to give any solid answer on the subject of life after death.
The closest science has achieved to explaining life after death lies with people who have experienced, N.D.E (Near death experience). These are people who actually died for some short periods of time but was awaken. Most of them shared similar stories when they returned to life. Some claimed to have crossover to a place with unlimited space and time. Others like Anita Moorjani, a cancer patient who slipped into a coma in 2006 said her's was a beautiful place, so incredible it took away all her pain. She experienced herself above her body giving her 360-degrees peripheral view of the entire area. She said she also got united with her late father on the other who told her to return as it wasn't quiet her time to be there.
Be it heaven or hell, Valhalla or a magical place of unlimited time and space, whatever you may believe, the after life surely does exist. I guess someday everyone will find out which belief has it right on afterlife.