The .com, .net and .org top level domains are the longest established generic domains. This means that there are no restrictions on what names can be registered, and who can register them. They are by far the most widely used of all the top level domains.

Having a www.company.com website is the most common location for company websites, and is usually the first place people will try to find information on your company.

Registering in .com can help protect your company name and/or trademarks from being used by others, even if you don't yet want to set up a website.

Registering a .com domain is useful in giving the impression that a company is a "global entity" even if it just a small office with a PC and a telephone.

Because there are so few rules for registering a .com domain, and because of its global appeal, there are millions of domains registered already. This makes is less likely that your first choice of name will be available.

Having a www.company.com website may obscure the fact that you are located in Ireland, and may be a turn-off for people who habitually "Buy Irish".