All devices on the Web are recognized by a unique number called an IP address, for instance 123.123.123.123. If you have a website, the domain name that you type to open it is to save you time, yet the server where your site files are still has an IP. Considering that there are far more websites and devices than there're IPs, all shared website hosting servers have a number of websites under an identical IP, whereas with a dedicated server you'll get 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. An advantage would be that you'll have improved search engine rankings because a dedicated IP often means a quicker loading website. In addition, you need such an IP when you intend to acquire an SSL certificate for your site and secure the information that your visitors submit on it.