All devices on the World Wide Web are recognized by a unique number called an IP address, for instance 220.127.116.11. If you have a website, the domain that you enter in order to load it is for your convenience, yet the server where the site files are still has an IP address. Considering that there're many more sites and devices than there are IPs, all of the shared website hosting servers have a number of websites under the very same IP, while when you use a dedicated server you'll be given a dedicated IP as well. Even in the first case though, you can acquire 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 positions because a dedicated IP usually means a quicker loading site. What's more, you need such an IP when you intend to get an SSL certificate for your site and shield the data that visitors submit on it.