What is Adware?
Adware (Advertising Supported software) is an application that displays advertising in the form of banners and annoying pop-ups while you're running your computer. There are a number of other tricks adware applications have up their sleeve. It can change your Google and Yahoo search engine results into advertisements. Adware will also frequently advertisments in your Internet browser favorites and bookmarks along with putting them on your desktop and even in your start menu. A computer infected with adware will seem more like a billboard than a useful tool.
Adware is usually considered a form of spyware since adware often tracks personal information without their authorization.