All devices on the Web are recognized by a special number called an IP address, such as 188.8.131.52. In case you have a site, the domain name that you type to be able to load it is to save you time, however the server where the website files are still has an IP address. As there're a lot more sites and devices than there are IPs, all of the shared web hosting servers have a number of websites under an identical IP, while when you use a dedicated server you'll get a dedicated IP too. Even in the first case though, you can get a dedicated IP for your websites and host them on a shared server. One benefit would be that you will get improved search engine positions as a dedicated IP often means a quicker loading site. Last but not least, you need such an IP in case you intend to get an SSL certificate for your site and protect the information that visitors submit on it.