作业系统(operating system (OS))
控制电脑的许多不同操作及管理、协调电脑程式执行的软体。作业系统是调度由电脑执行的工作顺序，并把这些工作分配给电脑的各种硬体系统，例如中央处理器、主记忆体和周边设备。在载入、储存和执行程式时，以及在执行诸如存取档案、运行软体应用程式、控制显示器与储存装置和直译键盘命令等个别工作时，中央处理器都在作业系统管理下进行。当电脑同时执行几个工作时，作业系统便以最有效的方式分配电脑时间和各种资源，以分时系统来决定处理工作的优先次序，作业系统还管理电脑同网路中其他电脑的互动。现代电脑作业系统变得愈来愈与机器无关，能在任何一种硬体平台运作，目前最广泛使用的一种不拘平台的作业系统是UNIX。大部分个人电脑的作业系统是微软公司的Windows作业系统。
English version：
operating system (OS)
Software that controls the operation of a computer, directs the input and output of data, keeps track of files, and controls the processing of computer program. Its roles include managing the functioning of the computer hardware, running the applications programs, serving as an interface between the computer and the user, and allocating computer resources to various functions. When several jobs reside in the computer simultaneously and share resources (multitasking), the OS allocates fixed amounts of CPU time and memory in turn, or allows one job to read data while another writes to a printer and still another performs computations. Through a process called time-sharing, a large computer can handle interaction with hundreds of users simultaneously, giving each the perception of being the sole user. Modern computer operating systems are becoming increasingly machine-independent, capable of running on any hardware platform; a widely used platform-independent operating system in use today is UNIX. Most personal computers run on Microsoft's Windows operating system, which grew out of and eventually replaced MS-DOS. See also Linux.