Segmentazione, or network segmentation, is the practice of splitting a network into smaller zones with controlled communication between them. Instead of letting every device reach every other device, administrators place systems into separate segments and allow only the traffic that is truly needed. This can be done with VLANs, firewalls, access control lists, microsegmentation, and strict routing rules.
In cyber security, segmentation matters because it limits lateral movement. If an attacker compromises one workstation or server, segmentation can prevent that access from spreading to domain controllers, OT equipment, backups, or sensitive military systems. It also helps contain malware, reduce blast radius, and simplify monitoring by making unusual connections easier to spot. In defense environments and critical infrastructure, segmentation is especially important where availability and safety are as important as confidentiality. Good segmentation supports incident response, remote-access control, and change management, but only if exceptions are kept minimal and documented.