The collection of communication line and routers from the -
The collection of communication line and routers from the subnet.
The other bits in the IP address are don't care from routing point of view. The specification of bits that should be used for routing is specified by associating a subnet mask with a routing entry.
Subnet:-
A subnetwork or subnet is a logical subdivision of an IP network. The practice of dividing a network into two or more networks is called subnetting. Computers that belong to a subnet are addressed with an identical most-significant bit-group in their IP addresses.
Router:-
A router is a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet. A data packet is typically forwarded from one router to another router through the networks that constitute an internetwork until it reaches its destination node.