Definition:
Spyware is any software that has the ability to gather information about a computer user, usually without the user's knowledge. Spyware may be distributed as part of low-cost or free Internet services, or hidden in free or low-cost software downloads.
Spyware is sometimes above board, at least technically. Software licenses or online service agreements may acknowledge the existence of the spyware, but because so few individuals ever read the wordy and overly complex documents, they aren't aware that they're agreeing to the use of the spyware.
Examples:
Spyware is most often used to covertly gather information about an individual's web browsing habits for advertising or marketing purposes, although it can also be used to gather personal information.
