Windows Vista® Inside Out Deluxe Edition

Blocking Viruses and Worms with an Antivirus Program

A virus is a computer program that replicates by attaching itself to another object. Viruses can infect program files, documents (in the form of macro viruses), or low-level disk and file-system structures such as the boot sector and partition table. Viruses can run when an infected program file runs; they can also reside in memory and infect files as the user opens, saves, or creates the files. A worm is a standalone program that replicates by copying itself from one computer to another, usually over a network or through e-mail attachments. The distinction between viruses and worms can be blurry and for practical purposes is unimportant.

Historically, the most common source of widespread computer ...