ICANN is the Internet Corporation for Assigned Names and Numbers. Put simply, it is a nonprofit organisation established in 1998 which ensures that the internet runs in a stable and secure manner through technical maintenance and policies. It manages the domain name system [DNS] which makes the internet easily usable by allowing people to go to website through easily memorable domain names instead of accessing them through a series of numbers which are called IP addresses. 

Some of ICANN's responsibilities include: 

• Managing the IP addresses which is a unique identifier assigned to every device connected to the Internet, for example PCs and smartphones, but also printers and gadgets. 
• Manages IANA which is responsible for the administration of domain names. New domain name extensions will have to be pitched to ICANN.
• Managing the DNS root server systems which a hierarchical system of thirteen root domain servers which resolve Top Level Domains, such as .uk or .com.

ICANN is managed by a board of directors and is made up of three supporting organisations, as well as various sub-groups, committees, working groups, and advisory committees including the Governmental Advisory Committee which includes representatives from over 100 countries. 

In 2013 ICANN produced this video about their inner workings and global responsibilities: