The way that competition is supposed to work between registries, is that lots of companies go to ICANN and say “We think we can reliably manage .com, and we think it would cost us [$5] per domain.” ICANN reviews these bids and awards the .com contract, which lasts for a fixed period of time, to whomever they deem best-suited to the job. In this time, other companies can think of ways to manage .com better/cheaper, and try and win the next contract. This, in theory, would provide an incentive for registries to innovate, a big part of which would be in lowering costs.
Next, someone has to tell the rest of the Internet that google.com points to 220.127.116.11. This is done by a “registry”, which is also the wholeseller that provides domains to registrars. Each top-level domain (TLD) — .com, .net., .org etc — has a registry that manages it. The .com TLD has been managed by the same registry since the beginning of time — an extremely profitable monopoly called Verisign. More on that later.
If you're having trouble finding a domain name (whether because of crowding or cyber-squatters), check for a help facility on each registrar's site. Domain registrars typically house search engines that return a listing of available names similar to the one you want. When you search for a domain name at Namecheap, for example, you get both the status of that name and a list of suffixes available for that name. Maybe [Sitename].com isn't available, but [Sitename].biz or .org is.
However, this can be a great way to start your online journey. Especially if the domain you’re purchasing already has a strong backlink profile to give you a boost in the search engines. Once you purchase a domain from Flippa you’ll need to register the domain with a new registrar and choose a host as well. Depending upon the details of the sale and where the current domain is registered and hosted.
Who is in charge of all of these processes? Most countries manage a Network Information Center (NIC). An NIC is the main database that has all the information regarding what domain names have been registered and the IP address associated with each of those domains. The nonprofit organization the Internet Corporation for Assigned Names and Numbers (ICANN) is in charge of creating and managing the procedures for internet namespaces.