Acupressure is often called acupuncture without the needles. Instead of needles, acupressure involves the application of manual pressure (usually with the fingertips) to specific points on the body.
According to the principles of traditional Chinese medicine, the body has invisible lines of energy flow called meridians. There are thought to be at least 14 meridians connecting our organs with other parts of the body. Acupuncture and acupressure points lie on those meridians.
If the flow of energy (also called "chi" or "qi") is blocked at any point on a meridian, it's thought to cause various symptoms and health conditions anywhere along the meridian. That's why a practitioner may apply pressure to an acupressure point on the foot to relieve a headache.