Hey kiddo, do you know what happens when someone dies? When someone dies, their body stops working and they can't breathe or eat anymore. This is called death. Thanatos is a Greek term for death, and it's often used to describe the personification of death in mythology. It's kind of like a scary character that people in ancient Greece believed took people's souls to the underworld after they died. So, thanatos is really just a fancy way of saying death. Does that make sense, kiddo?