Separated from the Internet. Air-gapped computer systems contain highly sensitive data and are connected via private networks that are completely isolated from the Internet. A firewall between the network and the Internet does not make the network air gapped. It has to be physically isolated with "air in between."
To gain access and inject malware, an attacker would have to literally sit down at the air-gapped computer and insert a USB drive. A user on a computer without any wired or wireless network connection whatsoever is essentially working on an air-gapped computer. See Faraday cage
, cold wallet
, computer security
and information security
From Wireless to Wired
Another use of the air gapped term is when a Wi-Fi network is changed to Ethernet in order to prevent eavesdropping. See Ethernet