What are malware, spyware, and cookies, and what differentiates them?

Malware is short for malicious software and is typically used as a catch-all term to refer to any software designed to cause damage to a single computer, server, or computer network, whether it's a virus, spyware, et al.

Spyware is a type of malware that is installed on computers and collects information about users without their knowledge. Spyware programs can collect various types of personal information, such as Internet surfing habits, but can also interfere with user control of the computer in other ways, such as installing additional software and redirecting Web browser activity. Spyware is known to change computer settings, resulting in slow connection speeds, different home pages, and/or loss of Internet or functionality of other programs.

In computing, a cookie (also tracking cookie, browser cookie, and HTTP cookie) is a small piece of text stored on a user's computer by a web browser. A cookie can be used for authenticating, session tracking (state maintenance), and remembering specific information about users, such as site preferences or the contents of their electronic shopping carts. They are neither spyware or viruses, although cookies from certain sites are detected by many anti-spyware products because they can allow users to be tracked when they visit various sites.

What exactly is a virus? Is a "worm" also a virus?

Viruses are computer programs or scripts that attempt to spread from one file to another on a single computer and/or from one computer to another, using a variety of methods, without the knowledge and consent of the computer user. A worm is a specific type of virus that propagates itself across many computers, usually by creating copies of itself in each computer’s memory.

Many users define viruses simply as trick programs designed to delete or move hard drive data, which, strictly speaking, is not correct. From a technical viewpoint, what makes a virus a virus is that it spreads itself. The damage it does is often incidental when making a diagnosis.

Obviously, any incidental damage is important, even when authors do not intend to create problems with their viruses; they can still cause harm unintentionally because the author did not anticipate the full effect or unintentional side effects. The most common method used for spreading a virus is through e-mail attachment. Sending a virus, even if designed to be harmless, can cause unforeseen damage.

How can I prevent a virus from infecting my computer?

A virus scanner is the most common tool for prevention. This utility attempts to scan a computer program before it runs, and if it recognizes the signature of a malicious code, it shuts it down. Many scanners also evaluate programs to determine if it contains any virus-related characteristics.

The best way to stop viruses is to use common sense. If an executable computer program is attached to your e-mail and you are unsure of the source, then it should be deleted immediately. Do not download any applications or executable files from unknown sources, and be careful when trading files with other users.

See our recommended free and paid security programs to download and protect your computer today.