Access-control systems manage who or what can enter a place or use a resource. They may combine credentials such as cards, PINs, or biometrics with readers, controllers, software, and connected services to authorize people, vehicles, or assets.
In cyber security, these systems matter because compromised accounts, administrative consoles, or network connections can expose sensitive access data or disrupt physical operations. Attackers may target the software and infrastructure behind a system, while defenders protect credentials, restrict administrative access, segment connected networks, and monitor for unusual activity. A reported ransomware claim against a vendor is a reason to review exposure, but it does not by itself prove that its systems were breached or affected.