All devices on the Internet are recognized by a specific number called an IP address, such as 184.108.40.206. If you have a site, the domain name that you enter in order to access it is to save you time, however the server where the website files are still has an IP. As there're a lot more sites and devices than there're IPs, all shared website hosting servers have a number of websites under the very same IP, whereas with a dedicated server you'll be given a dedicated IP as well. Even in the first case though, you can get a dedicated IP for your websites and host them on a shared server. An advantage would be that you may get superior search engine rankings as a dedicated IP often means a faster loading website. What's more, you need such an IP when you want to obtain an SSL certificate for your site and protect the information that visitors submit on it.