Have you ever heard of the companies GoDaddy, eNom, or Network Solutions? These companies are domain name registrars. Domain names are the way humans remember webpages, and websites. For example, google.com is a lot easier to remember than the IP address of the website 126.96.36.199.
Visitors of your website, want a domain name, rather than an IP address to remember, so they can view your webpages. Domain names used to be free, but now, just like everything else, they cost money. Usually around 10 to 20 dollars a year. The different registrars have different services that they offer, and pricing structures; but they all serve the same basic function. If you are thinking about creating a website, visit one of the registrars, and buy your domain name, before someone else gets it! You can buy a domain name that has already been registered, but then you end up paying hundreds to thousands of dollars for the domain!!