A bruise is a common injury that occurs when small blood vessels under the skin break, usually due to impact or trauma. This causes blood to leak into the surrounding tissue, resulting in a discoloration that can range from red to purple, blue, or yellow as it heals. Bruises can vary in size and may be tender to the touch. Most bruises heal on their own within a few days to weeks. To help reduce pain and swelling, people often apply ice or elevate the affected area. If a bruise appears without any known cause or does not heal, it may be a sign of an underlying health issue that requires medical attention.