Acupressure refers to the mild, finger tip pressure massage on certain meridian points of the body to stimulate the particular organs associated with these pressure points and to contract and relax the muscles.
Stimulating these points releases endorphins, which are chemicals that relieve pain. Pain is then blocked and the flow of blood and oxygen is increased to the affected area. Acupressure releases muscle tension, allowing the blood and energy to flow freely and allows toxins to be released and eliminated.
Other /More definition:
Acupressure refers to the application of pressure rather than needles to the points used in acupuncture. It is a healing technique.
List of books: Acupressure