RIR is the acronym for Regional Internet Registry and represents a not-for-profit international organization that deals with the allocation of Internet Protocol (IP) address space (IPv4 and IPv6) and the Autonomous System numbers within a geographical region.
Due to the Internet's rapid growth during the 1990's, the ISPs established Regional Internet Registries. The creation of RIRs was made based on the desire to develop the Internet through consistent global policies. The RIRs also work together on joint projects.
Nowadays, managing the space for Internet addresses involves the cooperation and communication between the five RIRs; which share a global responsibility though IANA. Over the last decade, the oversight for Internet address space has evolved into a simpler and more centralized system.
There are five RIR which represent different regions, they are:
- ARIN, the RIR responsible for the allocation of IP addresses for the region of North America, Canada, US and a portion of the Caribbean. It was established in 1997.
- RIPE NCC, originally known as "The Reseaux IP Europeens Network Coordination Centre," it is the RIR responsible for the allocation of IP addresses for the region of Europe, the Middle East and Central Asia. It was established in 1992.
- APNIC, the RIR responsible for the allocation of IP addresses for the region of Asia and the Pacific Rim. It was established in 1993.
- LACNIC, is the RIR responsible for the allocation of IP addresses for the region of Latin America and the areas of the Caribbean which are not covered by ARIN. It was established in 2001.
- AfriNIC, the RIR responsible for the allocation of IP addresses for the African continent. It became operational in 2005.
Each RIR has the main task to create and develop local policy for managing the allocation of identity elements such as unique Internet protocol (IP)addresses and numbers which are used by routers, switches and computers over the Internet. The main tasks/functions of each individual RIR are listed below:
- To provide appropriate registry documentation regarding the allocation of Internet Protocol address space (IPv4 and IPv6) and the Autonomous System numbers;
- To assist the development of Internet routing tables;
- To support the development of CIDR (Classless Inter-Domain Routing) techniques;
- To ensure protection against stockpiling and other types of manipulation that could lead to instabilities;
- The RIR represents the interests of its community by organizing forums and supporting the organizations involved in the coordination of the Internet.
RIR and IANA
IANA (Internet Assigned Numbers Authority) is the institution that allocates IP addresses to each individual RIR upon request. Then, each individual RIR is responsible for the allocation of addresses towards Internet Service Providers (ISPs), educational institutions, companies, government bodies and other such institutions. 
All RIRs participate in the body which was created to represent their collective interests, keep them in contact, and coordinate their efforts; known as the Number Resource Organization, it was founded in October, 2003 when the four RIRs decided to enter into a MoU. Later, when the RIR AfriNIC was created in 2005 it joined the MoU as well as the NRO.