All devices on the World Wide Web are identified by a specific number called an IP address, for instance 126.96.36.199. If you have a website, the domain that you type in order to open it is for your convenience, however the server where the site files are still has an IP address. Since there're far more sites and devices than there are IPs, all shared hosting servers have a number of websites under an identical IP, whereas with a dedicated server you'll get a dedicated IP too. Even in the first case though, you will be able to acquire a dedicated IP for your websites and host them on a shared server. One advantage would be that you may have improved search engine rankings since a dedicated IP often means a faster loading website. Furthermore, you need such an IP when you intend to obtain an SSL certificate for your site and shield the info that visitors submit on it.