Pathogenesis is the sequence of cellular events and reactions through which a disease develops, from initial exposure of the host to the appearance of clinical symptoms. In foodborne illness it covers how pathogens survive the stomach’s acidity, attach to intestinal cells, invade tissues or release toxins, multiply, and trigger the host’s inflammatory response. Understanding pathogenesis guides prevention at every level, since each step, from farm contamination to dose response in the consumer, offers a point where interventions such as cooking, vaccination of livestock, or competitive exclusion can break the chain. It also informs risk assessment, helping scientists predict how changes in processing or consumption alter the likelihood and severity of illness.