All devices on the World Wide Web are identified by a special number called an IP address, for instance 220.127.116.11. When you have a site, the domain name that you enter in order to load it is to save you time, however the server where your site files are still has an IP. As there are a lot more sites and devices than there're IP addresses, all of the shared website hosting servers have a number of sites under the same IP, while when you use a dedicated server you'll be given a dedicated IP too. Even in the first case though, you will be able to acquire a dedicated IP for your sites and host them on a shared server. An advantage would be that you will enjoy improved search engine rankings because a dedicated IP generally means a faster loading website. What is more, you need such an IP when you would like to acquire an SSL certificate for your website and secure the info that visitors submit on it.