There are randomly or intentionally triggered events. In the case of randomly triggered events, the time of occurrence cannot be predicted. It is different with the deliberately triggered events, such as when the operator interacts with the computer by pressing controls. For example, the event triggered by a keystroke or mouse click initiates a command that is implemented by the computer and shown on the display.
In microcomputer systems, such events generally trigger an interrupt, with the main program continuing to run first, and until the interrupt routine has completed the actions necessary to respond to the event.
Each event is logged as process information in a log file with important characteristic data such as the date and time, the start and end of the event, a description of the event, the triggering source, and so on.