Regional Internet registry
A regional Internet registry (RIR) is an organization that manages the allocation and registration of Internet number resources within a particular region of the world. Internet number resources include IP addresses and autonomous system (AS) numbers.
The Regional Internet Registry system evolved over time, eventually dividing the world into five RIRs:
- African Network Information Centre (AfriNIC) for Africa
- American Registry for Internet Numbers (ARIN) for the United States, Canada, several parts of the Caribbean region, and Antarctica.
- Asia-Pacific Network Information Centre (APNIC) for Asia, Australia, New Zealand, and neighboring countries
- Latin America and Caribbean Network Information Centre (LACNIC) for Latin America and parts of the Caribbean region
- Réseaux IP Européens Network Coordination Centre (RIPE NCC) for Europe, Russia, the Middle East, and Central Asia
The relationship between RIRs and IANA 
The Internet Assigned Numbers Authority (IANA) delegates Internet resources to the RIRs who, in turn, follow their regional policies to delegate resources to their customers, which include Internet service providers and end-user organizations. Collectively, the RIRs participate in the Number Resource Organization (NRO), formed as a body to represent their collective interests, undertake joint activities, and coordinate their activities globally. The NRO has entered into an agreement with ICANN for the establishment of the Address Supporting Organisation (ASO), which undertakes coordination of global IP addressing policies within the ICANN framework.
Number Resource Organization 
The Number Resource Organization (NRO) is an unincorporated organization uniting the five RIRs. It came into existence on October 24, 2003, when the four existing RIRs entered into a memorandum of understanding (MoU) in order to undertake joint activities, including joint technical projects, liaison activities and policy co-ordination.
AfriNIC, which was officially created in April 2005, joined on April 25, 2005.
The main aims of the NRO are to:
- Protect the unallocated IP number resource pool,
- Promote and protect the bottom-up policy development process of the Internet, and
- Act as a focal point for Internet community input into the RIR system.
See also 
- Country code top-level domain
- Geolocation software
- Internet governance
- Local Internet registry (LIR)
- National Internet registry