All devices on the Internet are recognized by a special number called an IP address, such as 18.104.22.168. In case you have a site, the domain that you type to open it is to save you time, but the server where your website files are still has an IP address. As there're far more websites and devices than there are IP addresses, all shared web hosting servers have a number of sites under the same IP, while using a dedicated server you'll get a dedicated IP as well. Even in the first case though, you're able to obtain a dedicated IP for your websites and host them on a shared server. An advantage would be that you may have better search engine positions because a dedicated IP generally means a faster loading site. In addition, you need such an IP if you would like to acquire an SSL certificate for your site and shield the information that visitors submit on it.