CIDR:
it used the technique of variable-length subnet masking (VLSM) to allow allocation on arbitrary-length prefixes For example, in the CIDR address 206.13.01.48/25, the "/25" indicates the network portion remaining are host portion.
http://www.cisco.com/en/US/tech/tk365/tk107/tsd_technology_support_sub-protocol_home.html
Route summarization:
summarization allows routing protocols to advertise many networks as one address , reason is reduce the routing table entries.
http://www.cisco.com/en/US/docs/ios/11_3/np1/configuration/guide/1ceigrp.html#wp18604
Supernetting:
Combining several IP network addresses into one IP address. Supernetting reduces the number of entries in a routing table and is done in CIDR addressing as well as internal networks.
http://www.cisco.com/web/about/ac123/ac147/archived_issues/ipj_9-1/ip_addresses.html
