All devices on the Web are identified by a special number called an IP address, such as 123.123.123.123. In case you have a site, the domain that you type in order to open it is to save you time, however the server where the site files are still has an IP. Because there're a lot more websites and devices than there are IP addresses, all the shared hosting servers have a number of websites under an identical IP, whereas with a dedicated server you'll have a dedicated IP too. Even in the first case though, you will be able to acquire a dedicated IP for your websites and host them on a shared server. One benefit would be that you will have far better search engine rankings since a dedicated IP often means a quicker loading site. Last but not least, you need such an IP when you would like to obtain an SSL certificate for your website and shield the data that visitors submit on it.