The ICANN community is the best place to know and to learn how Internet is working. ICANN plays a unique role in the infrastructure of the internet. Through its contracts with registries (such as dot-com or dot-info) and registrars (companies that sell domain names to individuals and organisations). ICANN help define how the domain name system functions and expands.

ICANN is "The Internet Corporation for Assigned Names and Numbers"

What is ICANN ?
ICANN is a not-for-profit public-benefit corporation with participants from all over the world dedicated to keeping the Internet secure, stable and interoperable. It promotes competition and develops policy on the Internet's unique identifiers. Through its coordination role of the Internet's naming system, it does have an important impact on the expansion and evolution of the Internet.

How ICANN works
At the heart of ICANN's policy-making is what is called a "multistakeholder model". This is a community-based consensus-driven approach to policy-making. The idea is that Internet governance should mimic the structure of the Internet itself- borderless and open to all.

ICANN is responsible for coordinating the maintenance and procedures of several databases related to the namespaces and numerical spaces of the Internet, ensuring the network's stable and secure operation. ICANN performs the actual technical maintenance work of the Central Internet Address pools and DNS root zone registries pursuant to the Internet Assigned Numbers Authority (IANA) function contract.
Much of  ICANN work has concerned the Internet's global Domain Name System (DNS), including policy development for internationalization of the DNS, introduction of new generic top-level domains (TLDs), and the operation of root name servers. The numbering facilities ICANN manages include the Internet Protocol address spaces for IPv4 and IPv6, and assignment of address blocks to regional Internet registries.
ICANN also maintains registries of Internet Protocol identifiers. ICANN's primary principles of operation have been described as helping preserve the operational stability of the Internet; to promote competition; to achieve broad representation of the global Internet community; and to develop policies appropriate to its mission through bottom-up, consensus-based processes.

To learn more about ICANN and Internet Governance, I recommend to take an online class at Online Learning Platform of ICANN.   https://learn.icann.org