Sepsis and septic shock are serious medical conditions that occur when the body's response to infection causes injury to its own tissues and organs. Sepsis is the third leading cause of death in the U.S., with over 500,000 cases annually and a 35% mortality rate. The document outlines the stages and definitions of sepsis, from systemic inflammatory response syndrome to septic shock. It also discusses the factors that contribute to the highest mortality rates, common clinical manifestations, appropriate diagnostic testing and treatment approaches.