This chapter covers the highlight of forensic taphonomy—that is how a body may decompose and the different stages that it goes through. Normal cell anatomy and physiology is covered and then the stages of decomposition that follow when the cells begin to die. Observable changes in early decomposition (algor mortis, livor mortis, and rigor mortis) are described and explained how they occur. Highlights of the putrefaction stages (including different color, bloat, etc.) are covered, followed by descriptions of the stages that follow including early decay, dry decay, and changes observed during skeletonization.