"What is ICANN?"
The Internet Corporation for Assigned Names and Numbers was created in October 1998 to assume control of the identifying aspects of the Internet such as domain names and IP addresses, to preserve the stability of the Internet, to broadly represent global Internet communities, and to promote competition. It has become the de-facto governing body and watchdog for the Internet naming system. ICANN also coordinates the stable operation of the Internet's root servers.
ICANN created the Shared Registry System, the domain name registration system for competitive registrars in the .com, .net, and .org top-level domains. Since then the number of domain extensions has continued to increase.
Another of ICANN's functions is to accredit registrars. Under the SRS, competing ICANN-accredited registrars register domain names utilizing shared, central registries.
You can find more information and be impressed with the scope of ICANN's work and responsibilities at their web site at http://www.icann.org