All devices on the Internet are identified by a special number called an IP address, for example 220.127.116.11. If you have a site, the domain that you type to access it is for your convenience, but the server where the website files are still has an IP address. As there are a lot more websites and devices than there're IP addresses, all the shared website hosting servers have a number of sites under the very same IP, while with a dedicated server you'll get a dedicated IP too. Even in the first case though, you will be able to obtain a dedicated IP for your sites and host them on a shared server. One advantage would be that you may have superior search engine rankings as a dedicated IP generally means a faster loading website. In addition, you need such an IP when you plan to buy an SSL certificate for your website and shield the data that visitors submit on it.