A Regional Internet Registry (RIR) is a not-for-profit organization that oversees Internet Protocol (IP) address space (IPv4 and IPv6) and the Autonomous System (AS) numbers within a specific geographical region. There are five regional RIRs across the globe: ARIN, RIPE, APNIC, LACNIC and AfriNIC. Together, they are known as the Number Resource Organization (NRO).
The Regional Internet Registries were were established by Internet service providers (ISPs) during the 1990s in response to the rapid growth of the Internet. They were recognized in RFC 2050 as a way to build consensus and establish a set of consistent global policies. Each individual RIR is tasked with creating local policy for managing the finite number of identity elements (unique addresses and numbers) that routers, switches and computers use on the Internet by:
- Providing a public registry documenting address space allocations and assignments.
- Assisting in the maintenance of Internet routing tables.
- Supporting Classless Inter-Domain Routing (CIDR) techniques.
- Preventing instabilities due to market distortions such as stockpiling or other forms of manipulation.