RIR
Regional Internet Registry

Although ICANN have overall responsibility for the global IPv4 and IPv6 address space, part of that responsibility is handed to each of the five RIR that operate around the globe. In basic terms, the RIRs are given chunks of IP address space which they are expected to manage. Those RIR include RIPE NCC, AFRINIC, APNIC, LACNIC and ARIN, each of which operate within their own region of the world. In turn, these RIR will further disseminate their IP address space allocations to national internet registries and ISPs.