Diverticulitis is an inflammatory condition that occurs when small pouch-like protrusions in the wall of the colon, known as diverticula, become inflamed or infected. These pouches are common in older adults and are often harmless (a condition called diverticulosis), but when inflammation develops, symptoms may include persistent abdominal pain—typically in the lower left side—fever, nausea, changes in bowel habits, and tenderness. In more severe cases, complications such as abscess formation, perforation, or bowel obstruction can occur. Risk factors include aging, low-fiber diet, obesity, smoking, and lack of physical activity. Treatment depends on severity and may involve antibiotics, dietary modifications, rest, and in complicated cases, hospitalization or surgery.