Active matter is composed of large numbers of active "agents", each of which consumes energy in order to move or to exert mechanical forces.[1][2] Due to the energy consumption, these systems are intrinsically out of thermal equilibrium. Examples of active matter are schools of fish, flocks of birds, bacteria, artificial self-propelled particles, and self-organising bio-polymers such as microtubules and actin, both of which are part of the cytoskeleton of living cells. Most examples of active matter are biological in origin; however, a great deal of current experimental work is devoted to synthetic systems. Active matter is a relatively new material classification in soft matter: the most extensively studied model, the Vicsek model, dates from 1995. (Text copied from Wikipedia, new material will come...)