All devices on the World Wide Web are recognized by a unique number called an IP address, for example 123.123.123.123. If you have a website, the domain name that you type in order to open it is for your convenience, yet the server where the website files are still has an IP address. Considering that there are many more sites and devices than there are IP addresses, all of the shared hosting servers have a number of websites under the very same IP, while using a dedicated server you'll get a dedicated IP as well. Even in the first case though, you're able to obtain a dedicated IP for your sites and host them on a shared server. One advantage would be that you may get far better search engine rankings since a dedicated IP usually means a faster loading site. What is more, you need such an IP if you intend to obtain an SSL certificate for your site and protect the info that your visitors submit on it.