Before you jump in and register your domain name you should be aware of what that registration entitles you to and what you can do with your domain. When you register a domain you do not own it, you can consider it to be like a rental agreement where you pay a fee and are entitled to use the domain until such time as it is due for renewal. You can renew the domain as many times as you wish or allow its registration to lapse if it is no longer required. Some domain types can be renewed for up to a decade in advance while others can only be registered or renewed for a set interval, usually two years.
While the domain is registered in your name it cannot be taken off you except in circumstances such as if the domain name infringes another entities copyright for example. If you do not renew your domain after the period of registration has expired there is usually a short period of grace between when it stops working and when it is returned to the pool of available domain names and can be registered by another person. Renewing your domain after it has expired but before it is released for registration by others can be substantially more expensive than the normal renewal fee. If you no longer require a domain name you can notify your registrar and it will be returned to the pool of available domain names but you will not receive a refund for the unused registration time.
When you come to choose your domain name you must decide what top level domain suits your needs. A top level domain is the last part of a domain name, the group of letters that follow the final dot of any domain name. For example, in the domain example.com the top level domain is com. Com is probably the most readily recognised top level domain and is one of the initial set of top level domains introduced way back in 1984 along with net, edu, gov, mil and org. These domains are considered to be general purpose domains and com, net and org despite their original uses are now in practice open to be registered for use by anybody for any purpose. They are often referred to as Generic Top Level Domains or GTLD's as they do not have a geographic or country designation. These original GTLD's have been expanded with aero, biz, coop, info, museum, name and pro added in 2000 and cat, jobs, mobi, post, tel and travel in 2005.
A country code top level domain or ccTLD is an internet top level domain generally used or reserved for a country or dependent territory, for example the domain example.com.au is considered an Australian website and example.vu is considered to be from Vanuatu. All ccTLD identifiers are two letters long and all two letter top level domains are ccTLD's. Different ccTLD's have different registration requirements, for many years au domains have required proof of a registered business and substantial relationship between the business and the domain name as an example. Not all ccTLD's have strict requirements for registration. Many ccTLD's are popular simply because their country abbreviation has a second meaning, for example Tuvalu's .tv domains are popular with sites associated with television.
A ccTLD can be useful for associating your domain with a particular region or country but be aware that many search engines including google rank your page accordingly and this will affect how your site appears in searches. Searching on google.com.au will return more au domains, which is fine if you only conduct business within Australia, but to your detriment if your business is based in the US. Choose your top level domain with care.
Finally, registering a domain name allows you to use that domain name for a web site address and for your email addresses but it does not actually provide these services. To display a webpage a webserver is required and a mailserver is necessary so that you can use your email addresses. So the world at large can find your web site and mailserver DNS or domain name servers are absolutely critical. Registering a domain name provides none of these things so you will have to find a host for your domain, a company that has these very necessary servers and charges a fee for their use. We cover this subject in much more depth in the
Hosting Services section of this site, for now it is just important to understand that there is a difference between registering and hosting a domain. Registering the domain can be summarised as renting the domain name itself and hosting can be considered to be the mechanism by which your domain is used and your web site presented to the world.