Classless Inter-Domain Routing (CIDR) is an IP addressing method that allows for flexible IP address space management without using the rigid framework of class addressing. This method allows to use the limited IP address resource sparingly, since different subnet masks can be applied to different subnets.
Standard syntax for writing IP addresses with a routing prefix. It consists of an IP address, a slash, and a number of bits to measure the routing prefix. Bits are applied to the address from left to right. 192.0.2.0/24 is an example of CIDR notation.