In this Did You Know...? article, we discuss two areas of concern for Internet users: viruses and spyware. We look at how to keep these types of vermin from infecting your computer and how to minimize the overall risk to your system. Internet vermin is everywhere, and any computer can easily be infected with a virus, Trojan Horse, worm, spyware, rootkit blended threat, or pop-ups. The types of malicious infections we can encounter are seemingly endless -- as are the types of programs available to consumers to help keep computer infections under control. iruses and AntiVirus Programs Defined A computer virus is a program or piece of code that is loaded onto your computer without your knowledge and runs against your wishes. All computer viruses are man-made and they can also replicate themselves by making a copy of themselves over and over again. Even such a simple virus is dangerous, because it will quickly use all available memory and bring the system to a halt. An even more dangerous type of virus is one capable of transmitting itself across networks and bypassing security systems.

When people talk about a computer virus, they generally call different types of computer viruses, like worms or Trojan horses a virus. While the words (Trojan, worm and virus) are often used interchangeably, they are technically not the same. However, what they have in common is that they all are malicious programs that can cause damage to your computer. They also can be found and removed by the same security program (for the purpose of this article, we also use the word virus to describe all three types of threats).

Editor's Recommendation: Need help understanding computer viruses? This Webopedia "Did You Know... The Difference Between a Virus, Worm and Trojan Horse?" technology article.

To protect your computer system from this type of malicious code, you can install and use an antivirus program. This utility scans hard disk drives for viruses, worms and Trojan horses and removes, fixes or isolates any threats that are found. Most antivirus programs include an auto-update feature that enables the program to download profiles of new viruses so that it can check for the new viruses on your system as soon as they are discovered.

Most antivirus programs can be run on your computer system in one of two ways. The first is as an on-demand scanner. This means the antivirus program actively scans your computer system for viruses only when you prompt it to do so, or by scheduling it as a time-specific task. On-demand scanners, while used to scan hard drives can also be used to check removable storage devices before copying from those devices onto your system.

The other option is to run the antivirus program as an on-access scanner. Here, the program runs in the background and actively scans your computer system constantly for viruses and other malicious threats, for the duration that your system is powered on, unless paused by the computer user. On-access scanners will monitor all system activity and automatically scan files that have been downloaded from the Internet or through e-mail.

Spyware and AntiSpyware Programs Defined

Spyware is software that covertly gathers user information through the user's Internet connection without his or her knowledge, usually for advertising purposes. Spyware applications are typically bundled as a hidden component of freeware or shareware programs that can be downloaded from the Internet; however, it should be noted that the majority of shareware and freeware applications do not come with spyware. Once installed, the spyware monitors user activity on the Internet and transmits that information in the background to someone else. Spyware can also gather information about email addresses and even passwords and credit card numbers.

Spyware is not a virus, as it does not replicate itself once on your system, but it is somewhat similar to a Trojan horse in that users unwittingly install the product when they choose to install something else.

Aside from the questions of ethics and privacy, spyware steals from the user by using the computer's memory resources and also by eating bandwidth as it sends information back to the spyware's home base via the user's Internet connection. Because spyware is using memory and system resources, the applications running in the background can lead to system crashes or general system instability.

Editor's Recommendation: Need help understanding adware and spyware? This Webopedia "Did You Know... The Difference Between Adware & Spyware ?" technology article.

Because spyware exists as independent executable programs, they have the ability to monitor keystrokes, scan files on the hard drive, snoop other applications, such as chat programs or word processors, install other spyware programs, read cookies, change the default home page on the Web browser, consistently relaying this information back to the spyware author who will either use it for advertising/marketing purposes or sell the information to another party.

To help protect against malicious spyware, users can run antispyware programs on their computer system. Antispyware programs are designed to search your hard drive for traces of known spyware and adware. Since spyware is installed like any other application on your system, it will leave traces of itself in the system registry and in other places on your computer. Antispyware software will look for evidence of these files and delete them if found, or prompt users  to remove or allow the marked files to remain on their system. Keeping it is something you should only do if you believe your antispyware program has detected a legitimate program as spyware.

The Similarities and Differences Between AntiVirus and AntiSpyware

Antivirus and antispyware programs work pretty much in the same way, the difference being the type of malicious file and pattern the program scans your hard drive (including the system registry) for  and detects. Today some antivirus programs include antispyware protection, and vise versa. While dual purpose and all-in-one software has its advantages, most industry experts still agree that for optimal protection, computer users should invest in both a good antivirus and a good antispyware program. 

Preventative Maintenance Tips