Beginners Article: This article attempts to introduce a topic, it avoids technical language and server settings.
Typically a domain name will identify your web site on the internet, for example hostvine.co.nz. Domain names have a named portion (the part you choose) and a suffix (.com .net .co.nz). The named portion must be unique for that suffix can not already be in use elsewhere. A domain name must be reserve by a domain name registra on your behalf and can be transfered from registra to registra.
A domain name must be reserved periodically, usually a registration fee occurs yearly. You can register a domain and see your options for registration here.
A domain name does not create or make avaliable a web site or email. You will need to aquire those services seperately.
If you would like to read more on the technical aspects of domain names, click here for the Wikipedia article on the subject.
Reserving a domain name doesn't automatically reserve other intellectual property rights. You may want to check to see if the name has been already used in other products or brands.
Your name must not be offensive or abusive.
For a domain name to be useful, it makes use of a Name Server (NS). The domain name will require to be directed to 2 or more Name Servers. This will usually happen automatically when the name is registered and will use the registra's own name server.
A Name Server contains a list of NS records to send different requests for Internet services such as email and web site traffic. Essentially the name server will receive a request for the location of something, for example a web browser want to use www.google.com, the name server will return an address of the server of where to find www.google.com, e.g. 126.96.36.199 and the web browser will go to that address and find the website.
If there records are incorrect, e.g. a NS record points to an incorrect place then actions such as locationing a web site will fail.
Sub Domains: A domain using your main domain at the end. For example maps.google.com. www.google.com is also considered a sub domain name.
Parked Domains: A domain name added to an exiting hosting account that already has a domain name. The website will responed to each domain name.
Pointers a Domain name: For your domain name to be used for web hosting or email, it must have a DNS record to point it to the correct server.