All devices on the Web are identified by a special number called an IP address, such as 184.108.40.206. When you have a site, the domain name that you type in order to open it is to save you time, but the server where your website files are still has an IP address. As there're many more websites and devices than there are IP addresses, all of the shared hosting servers have a number of websites under the very same IP, whereas when you use a dedicated server you'll have a dedicated IP too. Even in the first case though, you'll be able to get a dedicated IP for your sites and host them on a shared server. One benefit would be that you may enjoy far better search engine positions because a dedicated IP usually means a faster loading website. In addition, you need such an IP if you plan to acquire an SSL certificate for your website and shield the data that visitors submit on it.