Acute appendicitis is one of the most common causes of emergency abdominal surgery in adults and children. Although tenderness at the McBurney point is the most specific symptom, diagnosing appendicitis clinically is challenging. Diagnosis should include the use of laboratory testing, including white blood cell count with differential, C-reactive protein level, and neutrophil-to-lymphocyte ratio, in addition to use of clinical prediction tools such as the Appendicitis Inflammatory Response score and diagnostic imaging. Although ultrasonography is a reasonable first-line imaging modality, its outcomes are user-dependent and studies are often nondiagnostic (ie, unable to rule out appendicitis). Computed tomography is commonly used in the United States to diagnose acute appendicitis and has the additional benefit of being able to evaluate for multiple etiologies of abdominal pain. Based on imaging findings, acute appendicitis can be subcategorized as uncomplicated (ie, inflammatory changes without signs of necrosis or abscess) or complicated (ie, signs of necrosis with perforation or abscess formation). Patients with appendicolith on imaging and pregnant patients should be managed surgically. The standard of care for uncomplicated acute appendicitis remains laparoscopic appendectomy, whereas complicated appendicitis in stable patients may initially be managed nonoperatively with antibiotic therapy and percutaneous abscess drainage before consideration of interval appendectomy.