Near-death experiences (NDEs) are vivid experiences that often occur in life-threatening conditions, usually characterized by a transcendent tone and clear perceptions of leaving the body and being in a different spatiotemporal dimension. Such experiences have been reported throughout history in diverse cultures, and are reported today by 10% to 20% of people who have come close to death. Although cultural expectations and parameters of the brush with death influence the content of some NDEs, near-death phenomenology is invariant across cultures. That invariance may reflect universal psychological defenses, neurophysiological processes, or actual experience of a transcendent or mystical domain. Research into these alternative explanations has been hampered by the unpredictable occurrence of NDEs. Regardless of the causes or interpretations of NDEs, however, they are consistently associated with profound and long-lasting aftereffects on experiencers, and may have important implications for non-experiencers as well.