Also called as Slash Notation
Represents the IP address with an n which is used to identify the Network ID from the IP address
e.g. 192.169.10.0/24

IP address is made of 8*4 bits = 32 bits.
/24 means 1st 24 bits is the Network ID. Network ID = 192.168.10
The remaining 8 bits can be used to connect = 256 devices

Usable Host Per Network = , where h is number of bits available
Each network has an Network ID and Broadcast ID that are not available for use (The 1st and the last IP)