Number Resource Organizations (NROs) are entities responsible for the allocation and management of internet number resources, which include IP addresses and autonomous system numbers. They ensure that these resources are distributed fairly and efficiently among users, such as internet service providers and data centers. NROs work collaboratively to maintain the global internet infrastructure. They include five regional organizations: ARIN for North America, RIPE NCC for Europe, APNIC for Asia-Pacific, LACNIC for Latin America, and AFRINIC for Africa. These organizations also promote best practices and provide support for network operators.