Spyware is, by definition, malicious software which unscrupulous people use in order to take control of someone else's computer without their consent. The perpetrators of spyware use the information they glean from your computer for their own benefit and purposes. Usually, spyware keecomps track of what you are doing with your computer, sends the information to ad websites, who in turn blast you with pop-ups more or less suited to your interests.

Some spyware programs, however, are designed for the purpose of stealing your identity. There are even programs called "anti-spyware" which are really just pretending to be helpful. They are in reality causing problems. Downloads, such as toolbars, are a prime source of spyware, so always be careful about such freebies. Also, be careful if you use Internet Explorer as your web browser, because more spyware is targeted at it than at other web browsers.

If your computer has become infected with spyware, you will probably have problems with your computer's performance. It can cause the computer to operate more slowly, or even cause a system crash. It can also cause you to have trouble making your connection to the Internet.

Spyware usually doesn't show up as a single program on your computer. More commonly, you will have many spyware programs if you have one. The effect of these unwanted programs usually becomes visible when your computer becomes much slower. Some of the spyware programs cause your firewall or anti-virus programs to stop working. In fact, sometimes one spyware program will disable another!

One reason that spyware slows down your computer is that it takes up the available disk space the computer would normally use in opening and running programs. Spyware is also designed to intertwine into your other programs so that it is difficult to remove.

Spyware also negatively affects the performance of your web browser so that you are bombarded with advertisements when you simply want to browse. Spyware can cause the settings of your web browser to change, and it can cause unwanted toolbars to appear on your computer.

Fortunately, there are legitimate and effective anti-spyware programs available for your computer. To be on the safe side, you should use such a program that is produced by one of the major creators of anti-virus software, firewalls, and the like. A couple of reliable companies are McAffee and AVG. Be suspicious of pop-up ads for free anti-spyware programs, because these are likely to actually be spyware.

A final comment about anti-spyware programs is that they, like anti-virus and other security programs, require you to make frequent updates. These can seem like a nuisance, but they are essential to keeping things operating smoothly. Considering the millions of people who are using the Internet at any time, it's easy to see why updates would have to be made often.