The reaction of the tissues to any injury, which may be the result of trauma, infection or chemicals. Local blood vessels dilate, thus increasing blood flow to the injured site. White blood cells invade the affected tissue, engulfing bacteria or other foreign bodies; related cells consume any dead cells, thus producing PUS, after which the site starts to heal. The patient feels pain and the affected tissue becomes hot, red and swollen and may not function properly. If the infection is severe it may persist locally (chronic inflammation) or spread elsewhere in the body.