Air Gap Networks - What Are They?

The term air gap networks was popularized from defense and financial systems. It's a great concept in theory, but up to now it has been really hard to put into practice because the only way of moving data in and out of systems is by physical mediam. You literally have to take a us p stick, stick it into an art system, copy the data, and physically somebody has to walk out with it transported to a shared network. So we haven't seen these kind of systems really being deployed in enterprises and organizations.