"Dead" refers to the state of an organism that has ceased all biological functions necessary for life. This includes the stopping of the heart, breathing, and brain activity. When an organism is dead, it can no longer grow, reproduce, or respond to stimuli. In many cultures, death is often associated with rituals and beliefs about what happens afterward. For example, in Christianity, there are beliefs about an afterlife, while in Buddhism, the concept of reincarnation is significant. Understanding death is important in fields like biology, medicine, and psychology.