ARIN
ARIN (American Registry for Internet Numbers) is a non-profit organization that administers the distribution of many Internet resources, including versions of the IPv4 and IPv6 IP Addresses protocols and ASNs.
ARIN is also a Registrar for the national TLDs of several countries — including .ca (Canada) and .us (USA).
Additional information can be found on this website: https://www.arin.net/.