Subnetting divides a larger IP network into smaller segments, giving you tighter control over addressing, routing, and security boundaries. The CIDR prefix (like /24 or /27) tells you exactly how many bits belong to the network portion. From there, everything else — usable hosts, broadcast address, wildcard mask — follows from simple binary math that this tool handles automatically. IPv6 subnetting works the same way conceptually, though the address space is vastly larger and /64 is the standard prefix for local segments.