What is ICANN's purpose and why is it important?

ICANN is a public-private partnership that is responsible for the following functions related to internet names and numbers:

Allocation of IP address space: ICANN manages the distribution and allocation of IP version 4 and IP version 6 network addresses through five regional internet registries. These registries allocate IP network addresses and other internet number resources for their regions.
Top-level domain name system management: ICANN administers the DNS through accredited domain registrars. Registrars are authorized to sell domain names.
Protocol identifier assignment: ICANN maintains protocol identifiers, including reserved port numbers that internet protocols use and autonomous system numbers associated with global network routes.
Top level domain management: Generic Top-Level Domain (gTLD) and country code Top-Level Domain name system management.
Root domain name server system management: ICANN is responsible for maintaining the root domain server system.

These functions are important to maintaining the stability of the global internet and supporting uninterrupted global connectivity. ICANN must balance local, national, regional and international concerns while managing the DNS in a way that is acceptable to the majority of the world's internet users.