A subnet, or subnetwork, is a smaller network within a larger network that helps improve efficiency and manageability. The subnet is given by the Network part of the IP and the Host on that subnet is given by the remaining bits of the IP.
Subnet Mask
Let’s say the subnet mask is 26 bits long. You can notate this as <IP> 255.255.255.192 <IP>/26 The Network part is the first 26 bits and the Host part is the remaining 6 bits of the IP.