CIDR stands for Classless Inter-Domain Routing,

which is a method used to allocate IP addresses and IP routing. Here are some key points about CIDR:

Flexible Address Allocation:

CIDR allows for more efficient IP address allocation compared to the older class-based system (Class A, B, and C).

Prefix Notation:

It uses a prefix notation for defining IP addresses and their associated network masks. For example, 192.168.1.0/24 indicates that the first 24 bits are the network part of the address.

Aggregation:

CIDR supports the aggregation of IP addresses, which reduces the number of routes that need to be advertised and managed in the routing table (also known as super netting).