A subnet, or subnetwork, is a smaller network within a larger network. It helps organize and manage IP addresses more efficiently, allowing for better performance and security. By dividing a larger network into subnets, network administrators can control traffic and isolate issues more easily. Each subnet has its own range of IP addresses, which are used to identify devices within that subnet. This division allows for improved network management, as different subnets can be configured with specific rules and policies. Overall, subnets play a crucial role in optimizing network resources and enhancing communication.