How CIDR reduces the number of entries in a routing table?

Using classful IP addressing, a separate entry is needed in the routing table of a router for each network. This results in a routing table with a large number of entries due to the existence of a large number of networks. As each router has its own limitation, this large routing table will lead to reduced performance and eventual breakdown of the router. If CIDR addressing is used, a single entry can be used to represent a group of networks. This will reduce the number of entries in the router. This is known as route aggregation. The routes for the individual networks will be present in another router down the path. Each entry in the router will have a network prefix associated with it. The network prefix is used to identify the correct network from the given IP address.