死亡, or "death," is the end of life for an organism. It occurs when vital biological functions cease, such as heartbeat and brain activity. This process can happen due to various reasons, including illness, injury, or old age. In many cultures, 死亡 is viewed as a natural part of the life cycle. Different societies have unique beliefs and rituals surrounding 死亡, often reflecting their views on the afterlife or the continuation of the spirit. Understanding 死亡 helps people cope with loss and appreciate the value of life.