Flow is a term used in psychology to mean the mental state of a person completely immersed in an activity. It is an altered state of consciousness. The person is fully focused, performing actively and successfully. The situation is widely recognized by phrases like "in the zone", "in the bubble", "on the ball", "in the moment", "wired in", "in the groove". The performer almost loses touch with their surroundings: phrases like "lost to the world" reflect this mental absorption.