Spyware are computer applications that collect information about users browsing activity, preferences and interests. The data collected is sent to the creator of the application or third-parties, either directly or after being stored on the computer.

There are many different types of spyware operating on the Internet but you can generally group them into two categories: Domestic Spyware and Commercial Spyware.

Domestic Spyware

Domestic Spyware is software that is usually purchased and installed by computer owners to monitor the Internet behavior on their computer networks. Employers use this software to monitor employee online activities; some family members use domestic spyware to monitor other family members (such as reviewing the content of children’s chat room sessions).

A third party can also install domestic spyware without the knowledge of the computer owner. Law enforcement officials have used domestic spyware to monitor suspected criminal activity and criminals have used domestic spyware to siphon personal information from private computers in order to steal assets.

Commercial Spyware

Commercial Spyware (also known as adware) is software that companies use to track your Internet browsing activities. Companies that track your online habits often sell this information to marketers who then hit you with targeted advertising—ads that match your browsing interests and would most likely appeal to you.

Advertisers are delighted when they acquire such valuable marketing information so easily; in the past marketers had to bribe you to learn your preferences through contests, registration surveys and the like. Those methods of gaining your personal information still exist, but in those cases you have the power to read the fine print to learn the fate of your data and so could choose to consent or refuse. Gaining your preferences by stealth using software spies is far easier and offers a much more complete picture for the marketing industry; as a result, spyware is everywhere.

At the very least, spyware is a nuisance—slowing down your computer, filling your hard drive with useless gunk and marking you as a target for enterprising advertisers. Beyond intruding on your privacy, spyware can be used as a tool to perpetuate crimes, such as identify fraud.