Crohn's disease is a chronic inflammatory condition that affects the gastrointestinal tract. It can cause lesions from mouth to anus and may result in extraintestinal complications. The prevalence of Crohn's disease is increasing in adults and children. Genetic predispositions to Crohn's disease have been identified, and specific environmental factors have been associated with its development. Common presenting symptoms include diarrhea, abdominal pain, rectal bleeding, fever, weight loss, and fatigue. Physical examination should identify unstable patients requiring immediate care, include an anorectal examination, and look for extraintestinal complications. Initial laboratory evaluation identifies inflammation and screens for alternative diagnoses. Measurement of fecal calprotectin has value to rule out disease in adults and children. Endoscopy and cross-sectional imaging are used to confirm the diagnosis and determine the extent of disease. Treatment decisions are guided by disease severity and risk of poor outcomes. Patients commonly receive corticosteroids to treat symptom flare-ups. Patients with higher-risk disease are given biologics, with or without immunomodulators, to induce and maintain remission. For children, enteral nutrition is an option for induction therapy. All patients with Crohn's disease should be counseled on smoking avoidance or cessation. Patients with Crohn's disease are at increased risk of cancer, osteoporosis, anemia, nutritional deficiencies, depression, infection, and thrombotic events. Maximizing prevention measures is essential in caring for these patients.