AdWare is any software application in which advertising banners are displayed while the program is running. The authors of these applications include additional code that delivers the ads, which can be viewed through pop-up windows or through a bar that appears on a computer screen. The justification for AdWare is that it helps recover programming development costsand helps to hold down the cost for the user.
AdWare has been criticized for occasionally including code that tracks a user's personal information and passes it on to third parties, without the user's authorization or knowledge. This practice has been dubbed SpyWare and has prompted an outcry from computer security and privacy advocates, including the Electronic Privacy Information Center.

What is Spyware?

SpyWare is part of an overall public concern about privacy on the Internet. SpyWare is Internet jargon for Advertising Supported Software (Ad-ware). It is a way for shareware authors to make money from a product, other than by selling it to the users. There are several large media companies that offer them to place banner ads in their products in exchange for a portion of the revenue from banner sales. This way, you don't have to pay for the software and the developers are still getting paid. If you find the banners annoying, there is usually an option to remove them, by paying the regular licensing fee.

SpyWare can come in the form of cookies; information transmission, web bugs, and most are deliberately hidden so users are unaware of the SpyWare.

What is Theifware?

Thief-Ware is software being used in an unethical or disagreeable manner. The term does not necessarily mean that the software is involved in outright thievery or other serious criminal activity as determined by law.

Some of the software mentioned places links on victimized sites for visitors to click on, leading them away to other competitor sites. Many site owners would say the software is stealing visitors, which makes ThiefWare an appropriate name for such services and software.

Spying on Spyware (article news.com)

EarthLink and Webroot Software released a report Wednesday, revealing that nearly one of every three computers scanned in April for Trojan horse programs or system monitor spyware was infected.

Internet access provider EarthLink and security software maker Webroot scanned nearly 421,000 computers for their April Spy Audit report. Trojan horses and system monitors accounted for 133,715 pieces of the spyware found on those computers--representing almost one in three machines.

System monitors track users' computer activity, capturing virtually everything they do online. Trojan horses appear to be software programs a user has requested but actually aid hackers in stealing computer data. That information is then used to gain unrestricted access to users' computers while they are online.

"Consumers should be aware of the applications and files residing and running on their machines," Matt Cobb, Earthlink's core applications vice president, said in a statement. "While certain types of spyware are malicious, other programs can be used to improve their Internet experience."

Security experts note that the damage from Trojan horses or system monitors can sometimes be more severe than adware and adware cookies typically found on PCs.

When adding all four types of spyware found on the scanned computers during April, the Spy Audit Report found 11.3 million instances of spyware on the computers. That averaged 26.9 pieces of spyware per machine.

In March, 237,200 PCs were scanned, with 7.1 million pieces of spyware found on the computers. That averaged 30 pieces of spyware per PC, according to the report.

(http://news.com.com/Spying+on+spyware/2100-7343_3-5236735.html)