A decubitus ulcer, also known as a pressure sore or bedsore, is an injury to the skin and underlying tissue that occurs when there is prolonged pressure on the skin. This condition is most common in individuals who are bedridden or have limited mobility, as the constant pressure can restrict blood flow to the area, leading to tissue damage. Decubitus ulcers typically develop over bony areas of the body, such as the heels, sacrum, and elbows. They can range in severity from mild skin discoloration to deep wounds that expose muscle or bone. Prevention includes regular repositioning, maintaining skin hygiene, and using specialized mattresses or cushions.