RIRs, or Regional Internet Registries, are five subsidiary organizations that allocate and manage domains in cooperation with the Internet Assigned Numbers Authority (IANA).
The five RIRs and their respective regions are:
ARIN (American Registry for Internet Numbers) – United States, Canada, Antartica, and parts of the Caribbean.
RIPE NCC (Réseaux IP Européens Network Coordination Centre) – Europe, Russia, Central Asia, and West Asia.
LACNIC (Latin America and Caribbean Network Information Centre) – Latin America and the Caribbean (most of it).
APNIC (Asia-Pacific Network Information Centre) – East Asia, South Asia, Southeast Asia, and Oceania.
AFRINIC (African Network Information Centre) – Africa.