All devices on the Internet are recognized by a specific number called an IP address, for instance 126.96.36.199. In case you have a site, the domain name that you enter in order to access it is to save you time, yet the server where the site files are still has an IP address. Because there're a lot more websites and devices than there are IP addresses, all the shared hosting servers have a number of websites under the very same IP, whereas with a dedicated server you'll get a dedicated IP as well. 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 will have far better search engine rankings because a dedicated IP usually means a quicker loading website. Also, you need such an IP if you plan to obtain an SSL certificate for your website and shield the info that your visitors submit on it.