An Action is a response of the program on occurrence detected by the program that may be handled by the program events.
Many languages and frameworks use this noun as synonym of function, without return value, where its main purpose is to do something.
For example the .NET delegate Action represents a function without parameters and return value.
In the Unified Modeling Language (UML), an action is a named element that is the fundamental unit of executable functionality. The execution of an action represents some transformation or processing in the modeled system. An action execution represents the run-time behavior of executing an action within a specific behavior execution.
