Spyware is a type of malware that is installed on computers and collects little bits of information at a time about users without their knowledge. The presence of spyware is typically hidden from the user, and can be difficult to detect.
ADWARE
Adware is any software package which automatically plays, displays, or downloads advertisements to a computer after the software is installed on it or while the application is being used.
ANTI-VIRUS
Antivirus software is used to prevent, detect, and remove malware, including computer viruses, worms, and trojan horses.
Will security firms detect police spyware?
A recent federal court decision raises the question of whether antivirus companies may intentionally overlook spyware that is secretly placed on computers by police. Cnet News