Activity may refer to: Action (philosophy), in general Human activity: human behavior, in sociology behavior may refer to all basic human actions, economics may study human economic activities and along with cybernetics and psychology may study their modulation Recreation, or activities of leisure The Aristotelian concept of energeia, Latinized as actus Activity (UML), a major task in Unified Modeling Language Activity, the rate of catalytic activity, such as enzyme activity (enzyme assay), in physical chemistry and enzymology Thermodynamic activity, the effective concentration of a solute for the purposes of mass action Activity (project management) Activity, the number of radioactive decays per second Activity (software engineering) Activity (soil mechanics) , an aircraft carrier of the Royal Navy "Activity", a song by Way Out West from Intensify Cultural activities, activities referred to culture. See also Activity theory, a learning theory in education Social activity (disambiguation), several concepts in the social sciences Activiti (software), an open source Business Process Management platform Active (disambiguation)