Along with the .html extension, the HTML tags define the document as an html document. The HEAD contains information elements which can be read by browers, search engines, and spiders. The BODY contains the content which appears in the browser window. It is not yet required. The Internet is divided into groups known as domains which are further divided into subdomains.
Recent news claims that new agencies for the creation and registration of domain names is underway.
This includes the creation of new domain suffixes.