Near death experiences means your pronounced clinically dead not biologically. This means that basically your soul leaves the body and watches whats going on from above (Zukeran) seeing a light, entering a dark tunnel, seeing others, meeting a spirit, experiencing peace and then finally returning to the body. Many people have experienced it for example this girl that was near death was able to describe what her family did that night and ate. People can actually describe every little detail.
So by people having these experiences it still leaves many unanswered questions lingering around, like does something different happen to everyone? It just keeps me wanting to know more.
Zukeran , Patrick. "What happens after death." Probe Ministries 2002 01/05/08