A domain registrar, also know as a domain name registrar, is any company that offers the service which allows people to register a website domain name, so it becomes unique to you, preventing other users from registering the same name.
Until 1999, Network Solutions was the only company offering to register the top level domains: .com, .net, and .org. With the continuous growth of Internet users around the world, many other companies have joined the registrar business, and new top level domains were created to supply the growing demand for domain names.
All domain name registrars must receive accreditation by the Internet Corporation for Assigned Names and Numbers, or ICANN for short. ICANN is a non-profit company that has been responsible for allocating IP addresses and managing the Domain Name System which allows for users to navigate the web with friendly domain names rather than IP addresses.