Almost every computer I work on has some type of infection on it, whether it's spyware, adware, or other general malware. Most people say they have no idea how they got infected and end up asking the same questions.
First of all, what is spyware? Spyware is software that hides itself somewhere on your computer collecting information about you and what you do on the internet without your permission.
Spyware is often downloaded onto your PC when you download other free software. When you see a license agreement for any software you have downloaded from the internet be sure to read it carefully. Somewhere in the installation process there may be an option to install a free web toolbar, which could be spyware (Mywebsearch, Coolwebsearch, Weatherbug, etc).
Often buried in the license agreement will be a disclaimer saying that information about you and your browsing habits will be sent to the company's website. This kind of software slows down your computer and may install additional spyware as time goes on.
The information collected about you is usually for advertising purposes but spyware can scan files on your hard drive, listen in on other applications like chat programs, read cookies, etc.
Adware and Malware
Adware is a form of spyware which installs secret advertising software on your computer. These generate on-screen adverts (often pop-ups) which can be really annoying!
The worst forms of adware 'hijack' links in web pages. So, instead of taking you to the correct website they take you to a different site - who have often paid the adware makers.
Malware is another form of spyware. It's short for malicious software and is often designed to cause damage to your computer system just like a virus does. Some can even keep a log of every keystroke you have typed and steal your passwords and financial info.
These adware/malware applications can also seriously use up system resources and can cause your PC to slow to a crawl, crash or freeze. Some of them will even pretend to be anti-spyware programs, trying to fool you into clicking and further infecting yourself.
How You Get It
One of the most common ways spyware gets on your computer is the use of peer-to-peer file swapping programs such as Limewire, Bear Share. These programs not only come bundled with spyware when you install them, but many of the files you download using them are also infected. If you insist on using peer to peer file sharing programs, use Bear Share Lite or Lime Wire Basic instead. They have 0 spyware or adware included in the installation files.