The term domain name can be used in a wide variety of contexts, all of them relating in some way to the process of Domain Name System (DNS) registration. A domain name is basically a text based representation of what is a mostly numerical computer address, and makes it easier for humans to identify particular Internet pages. A domain name can be registered to identify a computer or group of computers on the Internet, and is also known as a hostname. This name will be a part of a website’s URL address registered by the domain name system, and makes it possible for a computer to be identified online. A domain name is a necessary abstraction that makes it possible for a website to change its physical IP address without needing to changes its humanly identifiable name.
For any individual or business wanting to have an online presence, choosing a domain name is one of the initial but crucial parts of the process. The registration of domains themselves has even become a big international business, with many people snapping up recently expired domains, auction domains, or looking for expiring domains in order to pick up a bargain. A good, short, and snappy domain name can be sold for millions of dollars in some circles, particularly if it relates to a highly profitable industry. Registered domain names are restricted to ASCII letters, numbers, and the hyphen - making for a limited number of combinations and permutations. The dot character is also used, but only as a way to separate the different aspects of the domain name structure.
Domain names are split up into a number of different levels, as a way to structure the domain name system and make it as efficient and easily understandable as possible. Top level domains include the well known names: com, org, and net, alongside the newer entries of biz, info, name, and a few others. There are also national top level names for most countries, such as uk for the United Kingdom, and au for Australia. Second level domain names are the ones found directly to the left of the top level names, and are the names actually chosen by people as a way to identify their website. If you go to the left again on a website address you can sometimes find a sub-domain. These are used as away to distinguish different parts of a website from one another.
