It tells you how many bits of the IP address belong to the network portion.
A network ID (or network address) identifies the subnet itself, not a specific device.
It is the first address in a subnet and is used by routers and devices to know which network an IP belongs to.
Example:192.168.1.0
A broadcast address is a special IP address used to send data to all devices within a subnet at the same time.
Instead of sending a packet to one device, the network delivers it to everyone in that subnet.
Suppose your subnet is:
192.168.1.0/24
Broadcast address → 192.168.1.255
Subnets are used to divide a larger IP network into smaller, manageable networks. They help with organization, performance, security, and efficient use of IP addresses.