All devices on the Web are recognized by a special number called an IP address, for instance 220.127.116.11. If you have a website, the domain that you enter in order to access it is to save you time, but the server where the site files are still has an IP address. Due to the fact that there are a lot more sites and devices than there are IP addresses, all the shared website hosting servers have a number of websites under the very same IP, while when you use a dedicated server you'll be given a dedicated IP too. Even in the first case though, you will be able to acquire a dedicated IP for your sites and host them on a shared server. One advantage would be that you will enjoy far better search engine rankings as a dedicated IP generally means a faster loading site. What's more, you need such an IP in case you plan to purchase an SSL certificate for your website and protect the info that your visitors submit on it.