All devices on the Web are identified by a special number called an IP address, such as 18.104.22.168. In case you have a website, the domain that you type in order to access it is to save you time, yet the server where the site files are still has an IP address. Considering that there're a lot more sites and devices than there're IPs, all of the shared hosting servers have a number of sites under an identical IP, while with a dedicated server you will have a dedicated IP as well. Even in the first case though, you can get a dedicated IP for your sites and host them on a shared server. An advantage would be that you may have superior search engine rankings as a dedicated IP often means a quicker loading website. Furthermore, you need such an IP if you would like to get an SSL certificate for your site and protect the info that visitors submit on it.