How Outlook helps to protect your computer from viruses

This article describes what viruses are and how Microsoft Outlook helps to protect your computer from them. For additional information about antivirus resources, see the Security Web site on Microsoft Office Online Support.

What is a virus?

Computer viruses attack the software of a computer, not the hardware. The basic definition of a virus is a program that copies itself. Most common viruses are small programs that need to use a legitimate program or file in order to run. Most viruses today are written with malicious intent; as a result, they can cause damage to programs or data. Because the virus code must be run to have any effect, the files that the computer treats as pure data, such as .txt files, are safe. For example, reading a plain-text e-mail message won't infect your computer with a virus.

In order to run, the virus code has to be written in an executable form, such as an .exe program file. HTML-format and RTF-format e-mail messages or Web pages that contain Microsoft ActiveX® controls or scripts, such as Microsoft Visual Basic® Scripting Edition (VBScript), Microsoft JScript®, or other types of embedded program code, can harbor virus programs that run when you open a message or view a Web page. Opening e-mail attachments can also infect your computer with viruses. Some malicious files can be constructed to take advantage of known vulnerabilities in the software in order to run destructive code. Microsoft recommends that you protect your computer by applying all updates and patches for the software on your computer.

source office.microsoft.com