Before neurons and their role in pain were understood, there have been many explanations to account for pain. Hippocrates (370-460 BCE) believed that it was due to an imbalance in vital fluids and in the 11th century Avicenna (980-1037) theorized that there were a number of feeling senses including touch, pain and titillation. Today we talk about four types of pain: 1) Nociceptive pain: Typically the result of tissue injury, 2) Inflammatory pain: An abnormal inflammation caused by an inappropriate response by the body's immune system, 3) Neuropathic pain: Pain caused by nerve irritation and 4) Functional pain: Pain without obvious origin. About 20% of adults have chronic pain and 7% of adults have chronic pain that frequently limits life or work activities, which increases with age. In this book we have gathered recent international research on pain and pain management from internationally renowned researchers from around the world, which we hope will be of interest to the reader.