A domain name is an online address and makes it easier to remember than a set of numbers. For example, www.example.com is easier to remember than 22.214.171.124:80. Domain names are made of parts and are separated by “.” so using the preceding example, the www is actually a sub domain so the domain name is really example.com (and the .com part is called a top level domain). The domain suffix (such as .com or .co.uk) is called a top level domain or TLD and these are managed by domain registrars.
You can either purchase from them directly from the domain registrars or through a reseller. Purchasing a domain name is easy and many places offer this service online just search for something like “buy domain name” in your favourite search engine and you’ll see plenty of them. You can usually enter the name part (“example” in the previous example) and the domain seller will give you a list of ones that have been previously registered as well as those that are still available.
You pick a domain name, pay a fee and then you own it for a period of time and no-one else can register that same name. At the end of the period, you get first option to renew the registration by paying a similar fee again. If you do not renew, the domain name will become available for anyone else to purchase on a first-come-first-served basis. You will continue to own and be able to use that domain name until you decide not to renew (most seller, set the domain to automatically renew using your debit/credit card so usually it take an action by you to cancel it before the renewal period expires. Some providers automatically renew your domain names a month or two before the expiry date, whereas others do it on the day it expires (check with your provider).
Now I mentioned before that the “www” in the example domain name was a sub domain. You don’t have to use “www” and example.com would be a perfectly valid domain name www.example.com and example.com would both usually go to port 80 on the server, which is the standard port for website traffic. You could also run other sub domains such as bob.example.com for say Bob’s blog or you could use the domain name for a service such as email with mail.example.com.
When choosing a domain name, you need the name itself and the suffix (TLD). You do not need to specify the subdomain and you can have as many subdomains as you want. Some of the more popular Top Level Domains and their intended purpose are:
However, the intended purpose has mostly been forgotten over time as domain names run out people and businesses use whatever name they can buy to suit their own purpose. The TLD is also largely irrelevant to search engines who base their categorisation on the websites content rather than the original purpose. There are two TLD’s that stand out above the others and have most names registered to them and that is .com and .co.uk (quite often company’s buy both to stop rivals getting the other). These two top level domains have usually been treated with authority above the others but do not despair if your chosen name is unavailable with those TLDs, the search engines will value your websites content above anything else and I think it won’t be too long before people start to do ignore the suffix too.