Domain Name or URL
A domain name is a website's address. Just as all addresses for physical locations (houses, buildings, etc.) are unique, each domain name is unique.
You can buy your domain name from numerous places on the Internet. But first you must check to see if it's available.
A domain name usually costs about $15 a year. It's best to buy your domain name from the same place you host your site, otherwise there are additional charges.