A subnetwork or subnet is a logical subdivision of an IP network. Think of the Internet as a massive city: an IP address is your street address, but a Subnet defines your specific neighborhood or gated community.
IP addresses are split into two parts: the Network ID and the Host ID. The Subnet Mask tells your computer where that split happens.
255.255.255.0 (Class C): Allows for 254 devices. Perfect for home Wi-Fi.255.255.0.0 (Class B): Allows for 65,534 devices. Used by large campuses.You might see an IP written as 192.168.1.0/24. The /24 is "CIDR notation." It is a shorthand way of saying the first 24 bits are the network, and the rest are for your devices.
By splitting a network, you prevent "broadcast storms" where every device shouts at every other device at once.
You can isolate your "Guest Wi-Fi" on a different subnet so they can't access your private home printer or server.
192.168.1.0/24 subnet by default.