Internet Corporation for Assigned Names and Numbers (ICANN) is a nonprofit corporation that is located in the United States of America. ICANN is responsible for managing critical name-spaces of the Internet, which are: Internet protocol namespaces and Domain Name System namespaces.
ICANN was founded on the 18th of September, 1998; and currently has it's head quarters in Playa Vista, Los Angeles, California. ICANN is under contract to the United States Department of Commerce, and an important department within ICANN is IANA. IANA is the department that administers many of the technical responsibilties of ICANN.
ICANN plays a critical role in maintaining the stability of the Internet. It performs a 'backbone' service for the Internet that maintains it's "smooth" functioning; without ICANN, the Internet would struggle to operate in a stable and functional fashion.
On the 1st of October, 2016, ICANN was freed from U.S. government oversight - ICANN will remain based in California - the U.S. has used its remaining influence over the DNS to move full control to ICANN, and not the UN or another International organisation body. The Internet has transitioned to multi-stakeholder governance; rather than one governed by a single nation state (U.S.).
The ICANN was founded in 1998 after a controversial incident involving Jon Postel - one of the primary individuals involved in the development of the Internet. Postel was managing IANA, which was a group/agency responsible for assigning names, numbers and symbols for the Internet. Due to dissatisfaction with Network Solutions monopolising the registration process for domain names, Postel was involved in a "test" which involved changing the root server that eight root nameserver "pulled" addresses from; this involved changing the root server from Network Solutions to IANA. Some critics have likened this "act" to a hijacking of the Internet.
Postel was condemned by political advisors to the US president, there were threats made to Postel that he "would never work on the Internet again"; this did not prove to be the case. The result of Postel's independent action, aka "infrastructure test", was that it led to the NTIA agency of the United States Department of Commerce to release a green paper which would lead to the creation of ICANN. IANA would become a department within ICANN, and oversight for IANA would be conducted by the NTIA agency of the United States Department of Commerce.
Jon Postel was to become the first chief technology officer of ICANN, but he died in 1998 of heart complications, and Esther Dyson took the job instead.
The Internet is comprised of computer networks which use the Internet protocol suite. One of the core protocols within this suite is the Internet Protocol (IP). The Internet Protocol (IP) routes packets of data across the Internet through the use of IP addresses inserted into the packet headers. IP addresses (numerical label) are assigned to every device which connects to a computer network that uses the Internet protocol suite for communication. The task of the ICANN is to administer the Internet Protocol (IP) address blocks (IPv4 and IPv6) and assign regional IP address blocks.
Alongside managing the Internet Protocol address space, the other 'key' role ICANN plays is in maintaining the Domain Name System (DNS). ICANN helps to maintain the root zone of the Domain Name System: the root zone is a nameless zone where top-level domains, like com and org, are created. The Internet Assigned Numbers Authority (IANA), overseen by ICANN, administer the DNS root zone. ICANN is responsible for creating new top-level domains (TLDs), gives contracts to registries (private companies) who manage a top level domain, and also decide which companies can register domain names within those top level domains for end-users.