Recently, a paradigm shift has occurred in the classification of diverticular disease and the understanding of its pathogenesis. Diverticular disease is now defined as a variety of clinically significant conditions such as diverticulitis, diverticular bleeding, symptomatic uncomplicated diverticular disease, and segmental colitis associated with diverticulosis. Low-grade inflammation, visceral hypersensitivity, abnormal intestinal motility, and genetic factors have emerged as the key contributors to the pathogenesis of diverticular disease. Routine antibiotic use is no longer recommended for all cases of diverticulitis, and simple recurrence is not an indication for surgical treatment. Early colonoscopy with proper preparation is recommended for the treatment of diverticular bleeding, although recent studies have not shown significant efficacy in preventing recurrence. The roles of dietary fiber, nonabsorbable antibiotics, 5-aminosalicylates, and probiotics in the prevention of diverticular disease are controversial and require further investigation.