All devices on the Web are recognized by a special number called an IP address, for instance 123.123.123.123. In case you have a website, the domain 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. Since there're a lot more sites and devices than there are IPs, all shared hosting servers have a number of websites under an identical IP, whereas when you use a dedicated server you'll get a dedicated IP as well. 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 may have far better search engine positions since a dedicated IP often means a quicker loading website. Last but not least, you need such an IP when you plan to get an SSL certificate for your website and secure the info that visitors submit on it.