All devices on the Internet are identified by a special number called an IP address, for example 18.104.22.168. If you have a website, the domain that you enter to be able to load it is to save you time, yet the server where your website files are still has an IP address. Since there are far more websites and devices than there're IP addresses, all shared web hosting servers have a number of websites under the same IP, whereas with a dedicated server you'll have a dedicated IP too. Even in the first case though, you'll be able to acquire a dedicated IP for your websites and host them on a shared server. An advantage would be that you'll enjoy superior search engine rankings because a dedicated IP usually means a quicker loading website. Last but not least, you need such an IP in case you want to acquire an SSL certificate for your website and protect the information that visitors submit on it.