Definition - What does Subnet Number mean?
A subnet number is a specific part of a subnet address in an IP address that identifies one among several subnets as the recipient or originator of a data packet. The subnet number helps browsers to accurately use the Internet to deliver messages to specific parts of a party’s full network.
Techopedia explains Subnet Number
Subnets are areas of a network based on groups of computers, either at a physical location or some other method of organization. The subnet number goes into the IP address as a specific indicator for where to send packets. Networking systems use something called a subnet mask to determine the part of an IP address that is a subnet number. The subnet number is typically located after the network number in the sequence.
Using subnets helps to minimize the use of full-network IP addresses that are a finite resource on the Web.