Spyware is a broad group of harmful software programs that can infect your computer and transmit information about you back to its owner. To avoid being infected by Spyware, it is necessary to install a good Anti-Spyware program that will detect and remove Spyware from your computer. A good Anti-Spyware program should also be capable of alerting you when a Spyware program tries to infect your computer. Today, there are a lot of free Spyware remover programs available online. Many of them are easy to download, install and manage, but their quality will vary so it is important that you look around and compare different free spyware remover programs before you make up your mind. You can also take advantage of the fact that they are free, and try several programs on your computer before you decide to stick with one of them. As of 2005, spyware is chiefly a problem for computer users that are running any of the Microsoft Windows operating systems. There are however a few spyware programs in the form of worms that are capable of infecting Linux and other Unix platforms. Installing a free spyware remover is therefore advisable regardless of which operating system you are using.

The very first free spyware remover was called OptOut and was created in 2000 by Steve Gibson of Gibson Research. Spyware had then been a problem for Internet users for several years. The first known use of the term "spyware" is from 1995, when a poster in Usenet made fun of Microsoft's business model. In the beginning, spyware was a term used for all types of espionage equipment, including tiny cameras for microfilming and similar. In 1999, the term spyware was used in a press release for new software from Zone Labs: the Zone Alarm Person Firewall. In the press release, the term spyware was specifically used for malicious software programs that send information back from an infected computer to the spyware owner. Today, the term spyware is rarely used for espionage cameras or other types of off-line equipment. The same year a very popular freeware, a computer game called Elf Bowling, began to spread among the Internet users. Eventually, the users found out that Elf Bowling included Adware, and that information about the players was sent back to the creator of the game, a company called Nsoft.

Today, many programmers and companies have created their own free spyware remover programs. It is very common that a free spyware remover can be upgraded to a more advanced version for a fee. As mentioned above, Steve Gibson created the first free spyware remover - OptOut. He was to be followed by free spyware remover programs from Lavasoft, the Ad-Aware spyware remover, and from Patrick Kolla - the Spybot Search & Destroy. Later SpySweeper from Webroot become one of the most popular free spyware remover programs. Naturally, Microsoft also developed their own free spyware remover. They bought the GIANT Anti-Spyware software and changed it into Windows AntiSpyware. The GIANT Anti-Spyware software is also licensed to Sunbelt Software and used in their free spyware remover program CounterSpy. Companies such as McAfee, Sophos and Symantec are also offering free spyware remover programs as a part of their anti-virus programs.