After death, the body cools down, becomes stiff, and then begins to decompose over time.

Immediately after death, the body starts to lose heat until it matches the temperature of its surroundings. Within a few hours, rigor mortis sets in — the muscles stiffen because energy for movement is gone. After a day or two, the stiffness fades, and the body starts breaking down as cells die and bacteria begin decomposition. This process can take weeks or months depending on the environment.