Air Gap refers to a way to isolate a PC from the big bad Internet and any other communications networks so as to have complete security with the information that resides therein. The protected computer doesn’t have any network or Wifi connection so in theory no one other than the user sitting in front of it can access its information. Air gaps have been around for many years, and have found their way into military and intensely secure installations as you might imagine.
However, air gaps aren’t foolproof. If you insert an infected thumb drive into the protected computer, you could compromise it completely. Over the past several years, researchers at Ben Gurion University in Israel have figured out other ways to break into air gapped computers, including using smartphones and other methods that I described in an article I wrote for ITWorld last year:
My article mentions some other methods that you can use to improve the security posture and better isolate your PC, such as removing or disabling USB ports and other removable media slots, and using virtual desktop infrastructure to isolate your desktop session to inside your own data center that can have a hardened security perimeter.