All devices on the Internet are identified by a unique number called an IP address, for instance 220.127.116.11. When you have a website, the domain name that you enter to open it is for your convenience, however the server where your website files are still has an IP. As there are far more websites and devices than there're IPs, all the shared website hosting servers have a number of sites under an identical IP, whereas when you use 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 websites and host them on a shared server. One benefit would be that you will enjoy superior search engine rankings since a dedicated IP generally means a faster loading website. In addition, you need such an IP if you want to get an SSL certificate for your site and secure the data that your visitors submit on it.