You will doubtless have noticed that the web addresses of most large international companies often take the form www.something.com, while the addresses of Irish companies are often www.something.ie. The end part of the address (.com or .ie) is called the top-level domain (TLD).

The most frequently used top-level domains for Irish based companies are (in order) .ie, .com, .net and .org. In addition, there are new TLDs which are starting to replace .com for general use: the two most recent being .biz and .info. UK companies or others that trade in the UK may also wish to register in .co.uk. Exactly which of these is the best depends on the image you wish your address to present. A .ie address indicates a real and substantive connection with ireland. The others have a more international feel.

There are many possible TLDs in which your domain name can be registered. Every country has a two-letter top level domain such as .jp (Japan) .no (Norway) and even the little used .us (USA). The Irish top-level domain is, of course, .ie. Rules and regulations for each of these domains vary, but in most cases, some form of connection to that country is required.

In addition, there are several other top-level domains, such as .com, .net, .org, .biz, and .info. These are the so-called generic domains. There is (almost) no restriction to who can register names in them. The .com TLD is by far the most popular domain internationally, followed closely by .net and .org. US companies register almost exclusively in .com, wheras UK companies (and those that trade with the UK) almost always register in .co.uk. The latest additions are .biz and .info, these are gaining ground fast.

Larger organizations frequently register their business name (and any trademarks) in all generic domains, plus those of any countries they operate in. Smaller companies usually register their business name in their own country and also in .com. If multiple domain names are registered, they can easily be pointed to the same or different web sites as and when required.