Answer:
The IANA organization was originally responsible for registering an IP address for an organization, and also handling domain name requests, and so forth.
IANA is now part of ICANN, which oversees these areas and others within the Internet.
One no longer has to register directly via IANA (which used to be the only way to get an IP address for your network in the past). You can register via other domain registrars and ISP organizations, which do the work for you.