A means to control the behavior of or within a process or system. There are many types of control mechanisms. Human decision making is a control mechanism made by an individual to start or delay a process in an attempt to keep or bring a process within a desired state. Control mechanisms can be physical such as limiting the number of trailers controls the number of deliveries that can be made at a given time. Software provides control by signaling whether a process should be started or delayed in order to achieve or maintain a desired state.