This chapter provides a background for human remains detection (HRD) dog handlers and/or those involved in death investigations. It is hoped that after reading this, one will be able to understand the basics of normal cellular function; of decomposition; products of decomposition; and, finally, to describe taphonomy and its application to investigations. There are different fields of taphonomy including biological, cultural, and geological. The application of forensics to taphonomy involves looking at the specifics of postmortem processes and what may have caused it to proceed the way it did. The body is made up of cells and those cells may be organized with similar or like cells into tissues, which make up organs, organs with similar functions are designated as systems, and systems make up the entire body. Every cell in the body has the same basic structure, which includes a nucleus, mitochondria, cell membrane, and other parts that one may remember from high school Biology class.