Visiting a web page where the web page author has intent to put items on your computer without your knowledge.
	Or by installing software where such programs are a part of the program you are installing.  An example of this are MP3 searching software, toolbars, etc.

Although there are thousands of various spyware and parasite programs, the following is a list of some of the more well known spyware and parasite programs:

Alexa, Aureate, Bargain Buddy, Brilliant Digital, CometCursor, Common Name, Cydoor, Ebates MoneyMaker, eUniverse Toolbar, Ezula, Favorite Man, Flashpoint/Flashtrack, Gator, Gigatech Superbar, Hotbar, Imesh, KaZaA, My Search, My Way, NCase, New.net, SaveNow, SearchAlot, Songspy, Trickler, WebHancer, Xupiter, xxxtoolbar, ZipClix.

If you see any of these names on your computer, keep in mind that as time passes, they will continue to add more spyware and parasite programs to your computer without your knowledge or consent eventually slowing your computer to an unusable state.

Removal

Sometimes removal of spyware and parasite programs result in the program detecting that there is an attempt of someone trying to remove it.  This detection can cause the spyware and parasite programs to hide themselves, rename themselves, cause damage to files, break the Internet connection, cause your PC operating system to not restart, etc.  The problem is worsened when there are hundreds of spyware and parasite programs on a single PC.

The average PC that we encounter on a call related to spyware and parasite typically has 300 to 600 programs.  The most we have ever encounted on one PC was slightly over 3,000!