V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):
Classless Internet Domain Routing [protocol] (RFC 1519)
The Free On-line Dictionary of Computing (30 December 2018):
Classless Inter-Domain Routing
(CIDR) /sid*r/ A technique that summarises a
block of Internet addresses in a routing table as an
address in dotted decimal notation followed by a forward
slash and a two-digit decimal number giving the number of
leading one bits in the subnet mask. For example,
188.8.131.52/24 specifies a subnet mask of
11111111.11111111.11111111.00000000 (binary), implying the
block of addresses 184.108.40.206 through 220.127.116.11.
CIDR is "classless" because it is not limited to the subnet
masks specified by Internet address classes A, B and C.
According to RFC 1519, CIDR was implemented to distribute
Internet address space more efficiently and to provide a
mechanism for IP route aggregation. This in turn reduces
the number of entries in IP routing tables, enabling faster,
more efficient routing, e.g. using routingprotocols such
as OSPF. CIDR is supported by BGP4.
See also RFC 1467, RFC 1518, RFC 1520.