Acute appendicitis is one of the most common causes of acute abdominal pain necessitating emergency surgical intervention worldwide. Despite more than a century of clinical and scientific investigation, appendicitis continues to pose significant diagnostic challenges because of its heterogeneous presentation, evolving epidemiological patterns, and overlap with numerous abdominal and pelvic conditions. This review synthesizes contemporary evidence on the epidemiology and diagnostic evaluation of acute appendicitis, with emphasis on global incidence trends and modern diagnostic strategies. Epidemiologically, acute appendicitis demonstrates marked geographic variation, historically affecting populations in high income countries more frequently, though recent data indicate rising incidence in low and middle income regions. Diagnostic approaches have evolved from relying solely on clinical examination to integrated algorithms that combine clinical scoring systems, laboratory biomarkers, and imaging modalities. Ultrasonography, computed tomography, and magnetic resonance imaging each play distinct roles, depending on the patient population and resource availability. safety, cost effectiveness, and reduced radiation exposure. Understanding the epidemiology and diagnosis of acute appendicitis remains essential for optimizing clinical outcomes, minimizing complications, and guiding future research priorities in this common surgical emergency.