Talk to any Internet marketer, and he (or she) will tell you: Naming your new online presence is just as important as learning how to build a website. But that begs the question: What is a domain name anyway? To many Internet users the answer is simple: "It's what you type in the address bar." Yes, but what is it?
Here is a good working definition of domain name: It's a label that serves as a marker for Internet content. Think of it as the Internet's equivalent of a telephone number. When someone dials your phone number, they get you; when someone types in your domain name, they get your web content.

Strictly speaking, the definition of domain name isn't quite that simple. The domain name system will support all of the letter and number characters you can type in, and a one punctuation mark (the hyphen, or dash - ).
The URL is usually (but not always) preceded in the address bar by http:// and three Ws, as in www, and will end in a period followed by a suffix (such as .com, .net, or .org), or a country code (.ru, .nz, and so on).
In terms of application, there's no such thing as "close" with domain names. For example, [www.fastcars.com] is not the same as [www.fastcars.org], which is not the same as [www.fast-cars.com] or [www.fastcars.ru]. For this reason, it is important when selecting a choice to make it as unique to humans as possible; otherwise, people trying to remember your domain name will remember someone else's domain name by mistake.
Domain names are registered, and the registry servers maintained, by domain name registrars. These are businesses that make money registering the domain name you choose (assuming it isn't already taken) and making sure that it points to your content.

Finally, no definition of domain name would be complete without touching on the subject of the IP address. IP means "Internet Protocol," and an IP address is a series of four three-digit numbers separated by periods (or dots).

The IP address is a unique identifier for every computer on the internet, and so in this manner it functions much like a domain name does.
However, it is much easier to remember [www.IamaDomainName.com] than it is to remember [201.175.003.051].