Just days after Verisign launched the Site Finder Service, ICANN wrote a strongly worded letter ordering them to disable it. Verisign complied, but not without writing a strongly worded letter of their own, in the form of a lawsuit. Verisign argued that ICANN overstepped their bounds in trying to control their activities, and ICANN argued… that Verisign overstepped their bounds in performing those activities.
A handful of domains will have restrictions on them, which means you can only purchase them if you meet certain criteria or have authorization (some examples are .gov, .edu. and .mil). But most extensions are available to everyone. In fact, most country code Top Level Domains (ccTLDs) are available for anyone to purchase, even if you don’t reside in the country in question.

The right to use a domain name is delegated by domain name registrars, which are accredited by the Internet Corporation for Assigned Names and Numbers (ICANN), the organization charged with overseeing the name and number systems of the Internet. In addition to ICANN, each top-level domain (TLD) is maintained and serviced technically by an administrative organization operating a registry. A registry is responsible for maintaining the database of names registered within the TLD it administers. The registry receives registration information from each domain name registrar authorized to assign names in the corresponding TLD and publishes the information using a special service, the WHOIS protocol.
A few companies have offered low-cost, below-cost or even free domain registration with a variety of models adopted to recoup the costs to the provider. These usually require that domains be hosted on their website within a framework or portal that includes advertising wrapped around the domain holder's content, revenue from which allows the provider to recoup the costs. Domain registrations were free of charge when the DNS was new. A domain holder may provide infinite number of subdomains in their domain. For example, the owner of example.org could provide subdomains such as foo.example.org and foo.bar.example.org to interested parties.
Domain names serve to identify Internet resources, such as computers, networks, and services, with a text-based label that is easier to memorize than the numerical addresses used in the Internet protocols. A domain name may represent entire collections of such resources or individual instances. Individual Internet host computers use domain names as host identifiers, also called host names. The term host name is also used for the leaf labels in the domain name system, usually without further subordinate domain name space. Host names appear as a component in Uniform Resource Locators (URLs) for Internet resources such as web sites (e.g., en.wikipedia.org).

Domain investors build a portfolio of valuable domain names, and attempt to sell them at a profit. Both Sedo and Afternic offer domain marketplaces (also known as Domain Listing Services, or DLS) for investors to advertise their domains to potential buyers. Once the seller and buyer agree, the aftermarket platforms then facilitate the purchase and transfer of the domain(s). As an Enom customer, you’re entitled to list your domains for sale on Sedo, Afternic, or both at the same time. Get started
Finding the right domain name is the first step in building a website that people return to time and time again. Buying a good domain will inevitably boost your online presence, and therefore boost your success as a business or blog. Although it may seem like an investment of time as well as finances to build up a good domain, it's worth the effort. Content management systems (CMS) such as WordPress offer a good platform to build up a blog – 1&1 offers a WordPress CMS package, which includes a free domain for the first few months to get you started.
Second-level (or lower-level, depending on the established parent hierarchy) domain names are often created based on the name of a company (e.g., bbc.co.uk), product or service (e.g. hotmail.com). Below these levels, the next domain name component has been used to designate a particular host server. Therefore, ftp.example.com might be an FTP server, www.example.com would be a World Wide Web server, and mail.example.com could be an email server, each intended to perform only the implied function. Modern technology allows multiple physical servers with either different (cf. load balancing) or even identical addresses (cf. anycast) to serve a single hostname or domain name, or multiple domain names to be served by a single computer. The latter is very popular in Web hosting service centers, where service providers host the websites of many organizations on just a few servers.
Domain names can be used in a number of ways. Direct visitors to your website’s home page or use complementary domains to send them to specific areas of your website ( e.g. yourcompany.jobs for a careers page). Or, forward a custom domain to an existing social media account, like your Twitter profile or Periscope channel. With a domain name you can even set up custom email addresses like yourname@yoursite.social, which can be used to conduct business or communicate with your followers. More.