All devices on the Web are identified by a specific number called an IP address, for instance 123.123.123.123. In case you have a site, the domain name that you type to be able to access it is to save you time, but the server where the website files are still has an IP. Considering that there're many more sites and devices than there're IP addresses, all shared website hosting servers have a number of websites under an identical IP, whereas with a dedicated server you will have a dedicated IP too. Even in the first case though, you will be able to get a dedicated IP for your sites and host them on a shared server. One benefit would be that you'll get better search engine rankings because a dedicated IP often means a quicker loading site. What's more, you need such an IP when you would like to buy an SSL certificate for your website and shield the information that your visitors submit on it.