What is the purpose of an air gap in cybersecurity?
An air gap serves to physically isolate a computer or network from the internet and other untrusted networks, so that sensitive systems have no direct connection an attacker could reach through. The purpose is to create a barrier that remote threats like hackers, malware, and network-based intrusions cannot cross, because there is literally no link to exploit.
Air gaps are used to protect high-value targets where a breach would be catastrophic, such as military and intelligence systems, industrial control systems, power grids, and financial infrastructure.
The protection is not absolute, though: data still has to move in and out somehow, usually via removable media like USB drives, which can carry malware across the gap (the Stuxnet worm is the classic example).
For that reason, an air gap is one layer of defense rather than a complete solution, and it works best combined with strict physical access controls and media-handling policies.
