离散事件仿真将系统随时间的变化抽象成一系列的离散时间点上的事件，通过按照事件时间顺序处理事件来演进，是一种事件驱动的仿真世界观。离散事件仿真将系统的变化看做一个事件，因此系统任何的变化都只能是通过处理相应的事件来实现，在两个相邻的事件之间，系统状态维持前一个事件发生后的状态不变。

A discrete-event simulation (DES) models the operation of a system as a discrete sequence of events in time. Each event occurs at a particular instant in time and marks a change of state in the system. Between consecutive events, no change in the system is assumed to occur; thus the simulation can directly jump in time from one event to the next.