The Center for Democracy & Technology [pdf]:

Unwanted advertising software or “adware” has evolved from an annoyance into a serious threat to the future of Internet communication. Every day, thousands of Internet users are duped into downloading adware programs they neither want nor need. Once installed, the programs bog down computers’ normal functions, deluging users with pop-up advertisements, creating privacy and security risks, and generally diminishing the quality of the online experience. Some users simply give up on the Internet altogether after their computers are rendered useless by the installation of dozens of unwanted programs.

One of the most troubling aspects of this phenomenon is that the companies fueling it are some of the largest, best-known companies in the world. In the following pages, the Center for Democracy & Technology (CDT) details how advertising dollars from major, legitimate companies are fueling the spread of nuisance and harmful adware1 and how those companies can help to combat the online scourge by adopting and enforcing good advertising placement policies.