In IP addressing, what does CIDR stand for?

CIDR stands for Classless Inter-Domain Routing. This method was introduced to improve the allocation of IP addresses and to help manage the growing number of networks and hosts on the Internet more efficiently.

Prior to CIDR, IP addresses were allocated based on classful addressing, which segmented the address space into fixed classes (A, B, and C), leading to inefficient use of IP addresses. CIDR allows for variable-length subnet masking (VLSM), meaning that a network can have a more flexible size and can be allocated more IP addresses based on its actual needs rather than being confined to the traditional classes. This saves address space and reduces the size of routing tables, promoting more efficient routing and addressing on the Internet.