All devices on the World Wide Web are identified by a unique number called an IP address, for example 123.123.123.123. In case you have a site, the domain that you enter to load it is to save you time, but the server where the website files are still has an IP. Because there are far more websites and devices than there're IP addresses, all the shared web hosting servers have a number of sites under the same IP, whereas using a dedicated server you'll get a dedicated IP too. Even in the first case though, you'll be able to get a dedicated IP for your sites and host them on a shared server. An advantage would be that you may enjoy far better search engine positions as a dedicated IP generally means a quicker loading site. Last but not least, you need such an IP in case you plan to purchase an SSL certificate for your website and protect the data that visitors submit on it.
