The Internet Assigned Numbers Authority (IANA) is an organization that oversees global IPv4 and IPv6 address allocation, autonomous system number allocation, root zone management in the Domain Name System (DNS), media types, Transport Layer port numbers and other Internet-related symbols and numbers.

IANA is a department of the Internet Corporation for Assigned Names and Numbers (ICANN), a non-profit private American corporation created in 1998 by the U.S. government and various other entities around the world.

IANA's main responsibilities include:

  1. IP address allocation: IANA coordinates the pool of globally unique IP addresses, ensuring that each one is unique and that regional internet registries have a supply to allocate to ISPs and other entities in their regions.
  2. Domain Name System management: IANA maintains the root zone of the DNS, which is the top level of the hierarchical DNS which all other domains are under.
  3. Protocol Parameters and Internet Standards: IANA works closely with the Internet Engineering Task Force (IETF) and other bodies to manage various protocol parameters - certain codes and numbers that software needs to interoperate. This includes port numbers, HTTP status codes, and many others.
  4. Management of the .int Top Level Domain: The .int domain is used for registering organizations established by international treaties between governments.
  5. Transport layer port numbers: IANA assigns and manages the registered port numbers for TCP, UDP, DCCP, and SCTP which are in the range of 49152 - 65535.

IANA plays a crucial role in the global internet infrastructure, managing the critical resources that are necessary for the internet to function and grow.