All devices on the Internet are recognized by a unique number called an IP address, such as 184.108.40.206. If you have a site, the domain name that you type in order to load it is to save you time, but the server where your site files are still has an IP. Because there are a lot more sites and devices than there're IPs, all of the shared hosting servers have a number of websites under an identical IP, while with a dedicated server you'll get a dedicated IP too. Even in the first case though, you'll be able to obtain a dedicated IP for your sites and host them on a shared server. One benefit would be that you may get far better search engine positions because a dedicated IP generally means a faster loading site. What's more, you need such an IP when you want to buy an SSL certificate for your website and shield the info that your visitors submit on it.