The World Wide Web is based on unique numbers known as IP addresses and every device or site that is part of the Web contains such an address. It would be pretty difficult to remember to visit 126.96.36.199 to open a website though, that's why a much simpler structure was introduced in the 80s - domains. Each domain name includes a primary part as well as an extension, to give an example domain.com or domain.co.uk. A wide range of extensions exist globally - part of them are assigned to countries, such as .co.uk in the aforementioned example, which is given to the United Kingdom, while various others are generic, for instance .com or .net. Some extensions are available for registration by any entity and others have certain requirements - business registration, local presence, etc. You're able to get a new domain name from a registrar company like ours and if the extension allows transfers, you can shift an existing domain name between registrars too.