Gastroenteritis, commonly referred to as stomach flu, is an acute inflammation of the gastrointestinal tract, marked by symptoms including diarrhea, vomiting, abdominal cramps, and fever. This review article provides a comprehensive overview of gastroenteritis, addressing its etiology, epidemiology, pathophysiology, diagnosis, management, and prevention strategies. The condition is caused by a variety of infectious agents such as viruses (noroviruses, rotaviruses), bacteria (Campylobacter, Salmonella), and parasites (Giardia lamblia), with transmission typically occurring through contaminated food, water, or person-to-person contact. Globally, gastroenteritis remains a significant public health issue, with high morbidity and mortality rates, particularly in children under five in developing countries. Diagnosis often relies on clinical evaluation and laboratory tests, while management focuses on rehydration therapy and symptomatic relief. Preventive measures include personal hygiene, food safety practices, environmental sanitation, and vaccination, with rotavirus vaccines significantly reducing severe cases in children. Emerging trends in gastroenteritis research aim at developing rapid diagnostic tools, novel therapeutic approaches, and new vaccines, highlighting the importance of a multidisciplinary approach to mitigate the global impact of this disease.