Advertising supported software, which has come to be more commonly referred to as adware, is a computer program and/or package of software under which advertisements or other marketing material are included or are just loaded automatically and played back to you over and over again after they install themselves. The main way that users are made aware that they have adware on their systems is through banner ads that appear in pop-up windows or a bar that might just appear on your computer screen.
The main reason that adware became as rampant as it did was that in the beginning it helped some developers recover the costs incurred during program development. Often times this was done with a disclaimer stating that if you use the reduced price option for this program, then you will receive periodic pop-up ads from sponsors. Another avenue for adware is under the category of shareware, which is where the user may download and operate an unregistered copy of a program for use completely free and receive pop-ups, or the user can choose to pay a fee and receive the full version free of any pop-ups. This is method is kind of like a status program, meaning the higher up you are the more benefits you receive.
There are some forms of adware that have been accused of including some sort of tracking code that monitors and reports a users habits online, thus making it a variable form of spyware. Other than these spyware types of programs, adware programs do not invisibly and unknown to you collect your data for reporting purposes.
This is where spyware and adware differ and that is the fact that adware does not purposely harm your system of confidence, where spyware while you have no idea it may be on your machine can gather personal and sensitive information about your identity and send it to third party sources.
While it may not be as harmful as spyware and Trojan programs, adware might be the most annoying of the three. There is nothing like surfing the Internet and have to close six pop-ups just because you wanted to check your email.
There are many programs available for free that will scan your system and help repair and remove any form of adware you have on your system. While most adware programs are merely a nuisance, there are those rare varieties that my still do harm to your system so proper maintenance is the key to a healthy system.
When not on his soapbox, Andrew Wroblewski is doing battle with the thousands of spyware programs that can affect you via his ant-spyware and spyware removal website: http://spyware.pcwash.com where you can get a free spyware scan of your computer system.