进程控制块(PCB)是系统为了管理进程设置的一个专门的数据结构。系统用它来记录进程的外部特征，描述进程的运动变化过程。(Process control block (PCB) is a specialized data structure in order to manage process settings. The system uses it to record the external features of the process, and describes the process of the movement of the process.)