A virus is a computer program that copies itself onto other programs and infects them. Similar to an easily spread disease, a computer virus goes from computer to computer, either adding to or changing the tasks a program is designed to do.

计算机病毒是一种计算机程序，它把自己的程序拷贝到其它程序上，从而传染病毒。和容易蔓延的疾病一样，电脑病毒由一个计算机传到另一个计算机，增加或改变原程序所执行的任务。