- software that is installed surreptitiously and gathers information about an internet user's browsing habits, intercepts the user's personal data, etc., transmitting this information to a third party: a parent's use of spyware to monitor a child's online activities.
- tools that are used to conduct espionage: sophisticated spyware that rivals that of the CIA.
- software installed via the internet on a computer without the user's knowledge and used to send information about the user to another computer
