STOPzilla is a esktop anti-spyware application built and sold by iS3. It detects, blocks and quarantines adware and spyware on personal computers that use Microsoft Windows operating systems. STOPzilla activates as soon as the user starts the computer and runs continuously for as long as the machine is on. The software can be set to scan the system automatically on a user-defined schedule or manually. Scanning parameters can be user defined as well, with a full scan analyzing the hard drive, memory, Windows registry and cookies for the presence of known spyware or potentially malicious activity. STOPzilla is typically purchased as an annual or multi-year subscription.