Answer:
your anti virus protects computer by the following:
Internet threats are blocked by your anit virus, any files that are downloaded are scanned before they enter your computer. Websites that you access are strictly scanned and updated on your PC. any pop ups blockers that try to send viruses to your PC is automatically blocked.
Removable Devices
any portable device that is connected to a computer is scanned and updated to the user. That includes portable usb's, external hard drives, DVD re-writers, discs,
Tracking cookies
cookies that save your usernames and passwords are recorded onto your machine. avg tracks these cookies and stops them from being shared.
Monitor
your anti virus is constantly monitoring your PC to see what is being installed and what's being removed. it records all the files that are either downloaded to your machine or uploaded to web.
other viruses
your anti virus controls other viruses such as worms, spyware, malware and adware to stop them from stealing your information or damaging your hard drive.