What Are The Parts of a Domain Name?
On the Web, the domain name is that part of the Uniform Resource Locator (URL) that tells a domain name server using the domain name system (DNS) where to forward a request for a Web page. For example, the domain name www.onlinepersonalssites.com locates an IP address for "onlinepersonalssites.com" at Internet point 220.127.116.11. The “www” refers to the host server. The file extension ".com" refers to the purpose of the company (in this example, "commercial"). It is known as the top-level domain name. The "onlinepersonalssites" part of the domain name defines the company and, together with the top-level file extension, is called the second-level domain name. The second-level domain name, what Web users are most used to, can be thought of as the "readable" version of the Internet address.
Further variance and additions can be used but are not required. A third level can be used to identify a particular host server at the Internet address if needed. For example, where "www" is the name of the server that handles Internet requests, a second server might be called "www2. Sub-domain levels can also be used. For example, you could have "www.yahoo.onlinepersonalssites.com” to lead a user to a specific subdivision on your site.
Second-level domain names (Remember: these are the “readable” versions of Internet addresses) must be unique on the Internet and registered with one of the ICANN-accredited registrars for the COM, NET, and ORG top-level domains. A top-level domain name can be geographic, but to register a U. S. geographic domain name or a domain name under a country code, you must see an appropriate registrar.
To allow multiple individuals, businesses, and organizations to have separate Internet identities while sharing the same Internet server more than one domain name can be mapped to the same Internet address.
An even higher level of domain exists than the top-level domain. It is the highest level known as the root domain. If the dot for the root domain were shown in the URL (which it is not) it would be to the right of the top-level domain name. However, the dot is assumed to be present, never shown.