What is adware?

Adware is software with advertising functions integrated into or bundled with a program. It automatically plays, displays, or downloads advertising material to a computer after the software is installed on it or while the application is being used.

Ideally, adware is considered a legitimate alternative offered to consumers who do not wish to pay for software, and ideally, adware does not do anything that you have not agreed to. The justification for adware is that it helps recover development costs for the programmer and keeps the software available for free.

But often adware is installed on your machine without disclosure and then it is considered spyware. Such programs are often delivered as part of another download you actually wanted, but without any notification. Since software licenses are rarely read, there is controversy over what is legitimate adware versus spyware.
Whether authorized or not, adware typically displays ads targeted to you based on key words that you enter in search engines and the types of Web sites you visit. The marketing data is collected periodically and sent in the background to the adware Web server. This personal information is often passed on to third parties.

Spyware and adware have become widely despised for their sneaky distribution tactics, unauthorised data gathering and tying-up of computer processing power, and the boundaries between spyware, adware and viruses have become blurred.
Hundreds of millions of PCs worldwide are infected with adware and/or spyware, and in 2004 analysts estimated that each PC installation netted adware firms $3 a year for a total annual revenue of $2 billion. In 2003, a large adware company revealed that its software was loaded onto 40 million PCs, bringing in $90 million in revenue a year.

Because of the big money involved, adware firms have widely skirted legal boundaries in the past, and trampled over the rights of many PC users by installing a variety of advertising software and spyware without adequate notification to the consumer.

This has led to numerous lawsuits. In November 2006, Internet advertising firm Zango Inc. agreed to pay $3 million to the U.S. government to settle allegations that its pop-up ad software was secretly installed on millions of personal computers. Zango allegedly installed adware more than 70 million times, causing 6.9 billion pop-up ads.