All devices on the Web are identified by a special number called an IP address, for instance 123.123.123.123. In case you have a site, the domain that you enter to be able to open it is for your convenience, yet the server where the site files are still has an IP address. Considering that there're far more sites and devices than there are IPs, all of the shared hosting servers have a number of websites under the same IP, while with a dedicated server you'll get a dedicated IP too. Even in the first case though, you'll be able to acquire a dedicated IP for your websites and host them on a shared server. One benefit would be that you'll get better search engine rankings because a dedicated IP generally means a faster loading website. What is more, you need such an IP in case you plan to purchase an SSL certificate for your site and protect the info that your visitors submit on it.