All devices on the World Wide Web are identified by a special number called an IP address, such as 18.104.22.168. In case you have a site, the domain name that you enter in order to open it is to save you time, however the server where the site files are still has an IP. Due to the fact that there are far more websites and devices than there're IP addresses, all the shared web hosting servers have a number of websites under the same IP, while with a dedicated server you'll be given a dedicated IP as well. Even in the first case though, you're able to acquire a dedicated IP for your sites and host them on a shared server. One advantage would be that you'll have far better search engine rankings as a dedicated IP usually means a quicker loading site. What's more, you need such an IP if you plan to obtain an SSL certificate for your website and protect the data that your visitors submit on it.