Everybody knows about, or has at least heard about what a virus is,
but do you really understand what they are, or how they spread?
What about pop-ups, trojan-horse programs, and spyware? Do you know the difference between a virus and a worm? On this page you can learn these things, learn how to prevent them, and even how to cure them!
A virus is simply a program that someone creates (usually a geek that has crossed over to the dark-side) that has the ability to spread to other computers. A virus usually (but not always) is destructive in some way. For example, a virus may search an infected computer for email addresses, email itself to all those addresses, then on some predetermined day, erase the entire computer!
The people that received the email that was automatically sent may open that email, infect their computer, and repeat the process. Although a virus is able to spread on it's own, it needs some sort of human interaction to infect a computer. Usually this means someone has to 'run' (double-click) the virus program. Virus writers usually use some kind of social-engineering to trick people into double-clicking their virus programs. This is why it is important to never open an email attachment that you were not expecting - EVEN if it appears to be from someone you know.
The worm is similar to the virus except for one detail. The worm requires no human help or intervention to spread itself! Worms rely on security 'holes' in Microsoft Windows, Microsoft Internet Explorer, or other systems/programs that allow them to automatically spread themselves over the internet. A security hole is simply an error or oversight in a program that when manipulated in just the right way, can be made to take control of the computer. Microsoft Windows and Microsoft Internet Explorer seem to have an abundance of this type of hole - however Microsoft usually calls them 'features'.
The Trojan Horse:
A trojan-horse is program that can do damage like a Virus or a Worm, but it does not have the ability to spread to other computers. Instead, the Trojan is disguised as something that it isn't - such as a fun game, sexy picture-file, etc. The user thinks he or she is getting something for free, when in reality they are getting much more than they imagined.
Spyware is software that is installed on your computer without your knowledge, remains hidden, and is difficult to remove. The purpose of spy-ware is usually to gather information about your web-surfing habits, your email addresses, or other personal information, and then transmit the information to it's "mother-ship" to be sold for marketing purposes.
Although spyware usually does not intentionally cause damage to your PC, it often slows it down or cause it to crash unexplainably. If you are using Microsoft Windows or Microsoft Internet Explorer, and your are an average user, and if you have not taken steps to prevent it, I can virtually guarantee that you have spyware on your PC right now!
The Pop-Up and it's cousin, the Pop-Under:
Popups and Pop-unders are advertising windows that appear out of nowhere on your screen (a pop up). Or appear below your open windows, so that when you close your programs you see the remaining 'pop-under' advertisement.
We have two types of these irritants. The innocent and the not-so-innocent.
The innocent popup (or popunder) appears when going to a website as a means for them to advertise something that you probably don't want. Most web-browser programs have built-in pop up blockers that can prevent this type of popup.
The Not-so-Innocent Pop Up is actually a form of spy-ware (see above). The purpose of this spyware is to generate advertisements that are always on your PC - no matter what you do, even when you aren't on the internet! This type of popup (or pop-under) usually advertises websites for pornography or gambling. If you've ever had this type of pop-up spyware on your PC you know how irritating it can be!
See our preventing viruses and spyware page to learn to prevent a virus or spyware.
If you think you already have a virus or spyware see our page on symptoms of a virus or spyware.