They are programs that you can run them at boot to scan your computer for spyware and adware (mainly anti-virus programs). Whenver it becomes next to impossible to boot up windows and run a scan. I boot up in DOS and run the scan there..it generally takes 2 or even 3 full scan to fully remove all the infections. Then, after I'm able to at least boot up into Windows safe mode...run another spyware scanner until everything is clean. Sometimes..even with all the scanners you can do anything 'bout it..I had to reformat but thats always the last choice.