This document defines terms related to sepsis such as bacteremia, septicemia, and SIRS. It describes the signs and symptoms of sepsis, severe sepsis, and septic shock. It discusses the epidemiology of sepsis, noting that it contributes to over 200,000 deaths per year in the US. Common pathogens that cause sepsis are also identified. The pathophysiology of sepsis is explained, including how the host recognizes toxins and the inflammatory response and control mechanisms involved.