Hesperian Health Guides
A bruise means that the tissue under the skin has been damaged and some blood is leaking out of the blood vessels. Bruises can hurt a lot and cause concern to the person, but they are usually not a problem. Treat a bruise the same way you would a sprain or strain: with rest, ice, compression, and elevation.
If you notice someone getting bruises often, or with several bruises at different stages of healing, it may be a sign of abuse. Gently try to find out if they are in danger and need help.