All devices on the Internet are recognized by a specific number called an IP address, for instance 220.127.116.11. In case you have a site, the domain that you enter to load it is to save you time, yet the server where the website files are still has an IP address. Considering that there are a lot more websites and devices than there're IP addresses, all of the shared website hosting servers have a number of websites under an identical IP, while using a dedicated server you will have a dedicated IP too. Even in the first case though, you're able to obtain a dedicated IP for your sites and host them on a shared server. An advantage would be that you may have better search engine positions since a dedicated IP often means a faster loading site. Furthermore, you need such an IP when you want to purchase an SSL certificate for your website and secure the information that your visitors submit on it.