A Regional Internet Registry (RIR) is an organization responsible for the allocation and management of Internet Protocol (IP) address space within a specific geographic region. RIRs ensure that IP addresses are distributed fairly and efficiently to Internet Service Providers (ISPs) and other organizations. They also maintain databases that track the allocation of these addresses. There are five main RIRs worldwide: ARIN for North America, RIPE NCC for Europe, the Middle East, and parts of Central Asia, APNIC for the Asia-Pacific region, LACNIC for Latin America and the Caribbean, and AFRINIC for Africa. Each RIR plays a crucial role in supporting the growth and stability of the Internet in its region.