Neutrophils are a key component of the innate immune system that play critical roles in the defense against invading pathogens. This wall poster depicts the major biological roles of neutrophils in health and disease. It covers the neutrophil response to pathogens, including phagocytosis, degranulation, inflammation, and NETosis, a mechanism unique to neutrophils. It is essential that these neutrophil defense responses are carefully balanced. As exemplified with NETosis, these same neutrophil defense mechanisms may also cause inadvertent injury to healthy tissues, leading to several pathophysiological conditions.