There are many different types of domain name. Two other international top domains, .net and .org , are becoming increasingly popular. .net is officially reserved for network associations such as ISPs, but in practice anyone can register a .net name. .org is supposed to be for non-profit organizations, but again this rule is not enforced and anyone can buy .org names. Anyone can register .net and .org domain names.
Most countries now have their own top domains, such as .uk for the UK or .fr for France.
Some countries have essentially sold their cyber-rights to enterprising entrepreneurs. Some companies are selling sub-domains of memorable domain names . These are NOT official, internationally sanctioned top domains, just companies essentially chopping up their own domain names into smaller pieces. You may have read about plans for several new top domains. 7 new top domains have been approved, but there are still a large number of disputes to resolve, and steps that have to be taken, before these new domains become available to register.