I first came across the near-death experience in Raymond Moody's book, Life After Life, which was first published in 1976. Recently the media have talked about "Near-death experiences" in connection with people who have narrowly missed being killed. The original meaning is that someone has died for a short while, has had a mystical experience in connection with their death and have then returned to tell their stories.
There are an increasing number of these stories because medical progress has meant that many people are revived after dying for a short while. What people report after a near-death experience seems to have some common threads although each experience is different.
Some people have returned to write books about their experiences and others have embarked on speaking tours. Some charge for the knowledge they have gained during their experience and others do not. Some claim to have gained insight into what happens for all of us, and others merely teach what they learned about themselves.
There is an increasing amount of information about near-death experiences which are now the subject of many youtube videos, ted talks and websites.
I will list or embed a selection here.