Spyware is computer software that gathers user information, usually for advertising purposes, without the knowledge or informed consent of the user. Spyware can monitor a user's web activity, scan files, create pop-up ads, log keystrokes, change the default page on the web browser, and even gather password and credit card information. Spyware removal software is software that scans your computer for viscious, data gathering programs that have found their way onto your PC. Spyware removal software ranges from free, do-it-yourself solutions like Lavasoft's Adaware, to full-featured, single-consumer products that usually retail for $40 or less. To this date, all known spyware can be deleted with spyware removal software, much of which is freely available.