Internet Assigned Numbers Authority
IANA is the acronym for Internet Assigned Numbers Authority and represents the entity that manages the allocation of global IP Addresses, root zone management related to DNS (Domain Name System) and other Internet Protocols (IP).
As the Internet evolved over time, there was a need for a centralized organization which would fulfill the followings tasks/needs:
- To take responsibility for managing parameters
- To make sure that everyone uses the same protocols and parameters
- To coordinate the assignment of identifiers
- To ensure that the creation and allocation of addresses and domain name is done accurately, based on principles which are acceptable for everyone.
The organization which was responsible for all these tasks/needs is IANA (Internet Assigned Numbers Authority). Even if at first IANA has only a few responsibilities,but due to the Internet growth during the 1990's there was also the need for an organization that would take responsibility over the central registration of Internet domain names and addresses. This is how ICANN (Internet Corporation for Assigned Names and Numbers) was created. 
Even if ICANN is now responsible with the centralization of registration tasks related to IP addresses, DNS assignment and protocol parameters management - ICANN does not replace IANA. There are many differences between ICANN and IANA, especially regarding their attributions, objectives and responsibilities.
IANA vs ICANN
IANA is the institution which runs TLDs (Top-Level Domains) and deals with the assignment of IP addresses and ranges, ports, and other related attributes. ICANN, based on the Memorandum of Understanding (MoU), is the institution which runs IANA.
- Besides managing the DNS root zone, IANA also manages the .int registry, and the .arpa zone;
- Regarding number resources, IANA is entitled to coordinate the global IP respectively AS number space, allocating these to RIRs (Regional Internet Registries);
- What concerns protocol assignments, IANA represents the main repository for number registries and protocol names. 
IANA is responsible for the administration of domain names which involves liaisons of TLD operators, with root name server operators, as well as operating with .int and .arpa zone.
In order to enable and better manage the allocation of Internationalized Domain Names (IDNs), IANA developed "IDN tables" which supply information related to admitted characters in different languages and other TLD related information. 
Based on IETF protocols, IANA is responsible with the administration of URI schemes (Uniform Resource Identifier) and character encoding for Internet use.
IANA is responsible with the delegation of IP Addresses towards RIRs. In their turn, each RIR (Regional Internet Registry( is responsible with the allocation of IP addresses depending on the zone/area they are managing. In the same way, when a RIR requests for more IP Addresses for allocation, IANA evaluates the request and is able to make an additional allocation for RIR.