There are three different kinds of software programs that are generically grouped into the definition of a virus. Those software programs are: the Virus, which attaches itself to another file on your computer's operating system; the Worm, which is a computer program that stands alone as an application that does not need another program to keep itself alive; and the Trojan, which is a software that disguises itself as something harmless such as a screen saver, and then infects your computer once it is executed.

The word virus as it relates to the corruption of your computer files can ultimately derail your whole life and send you in frenzy, depending on how badly your files are affected. When a virus wreaks havoc on a computer hard drive, it could simply mean the loss of a single file, or worse case scenario, essential work files.

Although it would be ideal to never encounter a computer virus in your lifetime, the odds aren't in your favor. Each year, word about some vicious pc computer virus generates so much fear from cyber world users across the nation and around the world. There is really no easy way to determine who will be infected by one of these debilitating apps, except for the fact that it can strike basically any computer user, especially those who accesses the Internet, or exchanges diskettes and CD's.

Even though most people aren't familiar with what exactly a virus is, they immediately understand that it is something bad. But viruses don't always have to be evil. By design, a virus is simply a computer program that is purposely written to install itself into computers without the consent of the person who owns the computer and is meant to replicate itself on other computers, whenever it has been executed.

The damage that sometimes occurs to computer files and system settings is the direct result of the virus software's intentional corruption of specific kinds of files and its intentional changing of system configuration files for the purpose of preventing the computer's operator from removing the virus from their computer. In recent years, the virus writers have become more sophisticated about writing code for the purpose of preventing the computer operator from removing the virus once it has been added to a computer. Some viruses will even block the computer's user from accessing anti-virus websites or gaining access to an online virus scan website.

Some viruses are designed to steal private information from a computer, including security-sensitive passwords and financial data.

Other viruses are designed to kill computers. One such example of a computer killer was the Michelangelo virus that was made famous by the press in 1992 when it erased the boot record of thousands of MS-Dos computers. It could also damage other operating systems, since it targeted the boot record, but it was only an annoyance on modern computers. By 1997, AV software companies such as the Norton Anti-Virus software made by Symantec, had wiped out the Michelangelo virus completely.

Viruses, Worms and Trojans, by nature are not always destructive little demons as most people are quick to assume. In fact, some are designed only to ride the computers open Internet connections, while remaining hidden from its user. One such virus this writer recently encountered was designed to launch a distributed denial-of-service (DDOS) against Microsoft Support services. That particular virus sucked up 80% of our network bandwidth from only one machine, and our network was designed to comfortably support the Internet activity of ten computers. In a DDOS attack, a computer will send requests to specific websites as frequently as the computer system can process those requests.

In all reality, not all virus attacks produce catastrophic results, but rather it depends on what activity the virus was designed to accomplish. In many instances, viruses don't even contain any destructive code. Viruses range widely in their effects, but most viruses cause relatively trivial problems, from the merely annoying to the downright insignificant. The reason this happens so frequently is because the person who coded the viruses made mistakes in their coding process, effectively rendering their own software useless. Often, the primary consequence of a virus infection is the cost you incur in time and effort to track down the source of the infection and eradicate all of its traces

But, all it takes is one ruthless virus rampaging through your computer files for most people to learn their lesson the hard way. All computer users should be familiar with the use of anti-virus software. If you are particularly fond of downloading files or free software from the Internet, or come into contact with foreign diskettes, then anti-virus software should be installed in your computer. Numerous brands of AV software are available online and at various computer stores.

In a lot of cases, it is also wise to pay a small subscription fee to ensure that your anti-virus software programs' definition file is always up-to-date. What many people fail to understand is that the day you download and install anti-virus software, the definitions are up-to-date in that moment. And the 90-day free trials, keep their own definitions up-to-date. But, virus writers are an adaptable bunch. If they find that the AV companies are effectively countering their previous accomplishments, then the virus writers will write new virus software that they hope will be more resilient and less affected by the AV companies who seek to wipe them out. There are in fact hundreds, if not thousands, of new viruses being written and deployed yearly.

If you download the free virus scan software packages, like those available directly from Symantec Norton or the one provided in the GooglePack software, made available courtesy of the search engine Google, you will get good coverage as long as those virus definition files remain up-to-date. With the free Norton Antivirus download provided in the Google Pack package, Google will ensure that your virus definitions will stay up-to-date for as long as Google continues to offer their free AV service.

It makes a lot of sense to get a comprehensive Internet security package to guard against all the different types of viruses that are sitting somewhere on the Internet, waiting for their opportunity to infect your computer. Organizations and individuals today need to have an all-inclusive virus protection policy to face the growing security threats of the Internet computer viruses. Given the rise in pc viruses within the last three years, many organizations have adopted a proactive management approach to the problem by installing an anti virus and content filtering software in order to identify and prevent computer viruses threats at the network server level.