Research into Near Death Experiences reveals that there are several common elements, which people report after returning back to their physical life.
Not everybody experiences all of these elements, some experience one or two while some lucky ones go through the complete set of these elements.
The most common one is the Out of Body Experience. I spans from seeing one's physical body lying in a hospital bed or fatally injured in an accident scene, observing it from above or from the side, to visiting one's loved ones in other parts of the town to moving at light speed to other cities or countries.
The second most common is the sensation of being completely free of pain and feeling a deep sense of peace after the initial shock of being separate from the body.
Perceiving time and space differently is the third most common element. Even though only a few minutes may have passed from physical death to the resuscitation, to the individual the experience itself may feel as if it had lasted for several hours. In the observed space may appear to be bigger or smaller, and some objects may appear or disappear which are not in the physical room.
Quite often people find themselves in other worlds, cities of light and different levels of existence. There some report of rooms of knowledge, judgement courts and similar, life reviews and knowing what the future will bring.
Many also report of the being light or the light itself, which emanates unconditional love. Once the NDE-ers experience themselves within the presence of the light they never want to leave again and certainly do not want to return back to their physical existence.
Greeters often appear, either in the form of previously deceased, angels or rarely even animals. In children's NDEs and terminally ill patients live greeters quite often appear - people who have already died but rarely also people who are still alive.
Here is a list of the 15 most typical elements collected from thousands of reported NDEs.
This talk held by Dr. Jen Holden is an amazing recollection of 30 years of Near Death Study: