Definition of keyboard for English Language Learners. : 1  a row or set of keys that are pushed to play a musical instrument (such as a piano) : 2  a musical instrument that is played by means of a keyboard like that of a piano and that produces sounds electronically. : 3  the set of keys that are used for a computer or typewriter.
Classless Inter-Domain Routing (CIDR, pronunciation: /ËsaÉªdÉr/ or /ËsÉªdÉr/) is a method for allocating IP addresses and IP routing. The Internet Engineering Task Force introduced CIDR in 1993 to replace the previous addressing architecture of classful network design in the Internet.
CIDR stands for Classless Inter-Domain Routing (occasionally, Classless Internet Domain Routing). CIDR was developed in the 1990s as a standard scheme for routing network traffic across the Internet. Before CIDR technology was developed, Internet routers managed network traffic based on the class of IP addresses. In this system, the value of an IP address determines its subnetwork for the purposes of routing.