All devices on the World Wide Web are identified by a special number called an IP address, for instance 22.214.171.124. When you have a site, the domain name that you enter to be able to open it is to save you time, but the server where the website files are still has an IP address. As there're many more websites and devices than there're IPs, all shared hosting servers have a number of sites under the very same IP, whereas using 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 websites and host them on a shared server. One advantage would be that you may enjoy improved search engine positions because a dedicated IP often means a faster loading website. What is more, you need such an IP when you want to purchase an SSL certificate for your website and shield the info that your visitors submit on it.