Microsoft Vista Viruses

A virus is a program or piece of code that “infects” other software by embedding a copy of itself in one or more executable files. When the software runs, so does the embedded virus, thus propagating the “infection.” Viruses can replicate themselves, and some (known as olymorphic viruses) can even change their virus signatures each time to avoid detection by antivirus software.

Unlike worms, defined next, viruses can’t infect other computers without assistance from people (a.k.a. you), a topic discussed in detail in the next section. One particular type of virus, a Trojan horse, spreads itself by masquerading as a benign application (as opposed to infecting an otherwise valid file), such as a screensaver or even, ironically, a virus removal tool.