All devices on the World Wide Web are recognized by a special number called an IP address, for instance 123.123.123.123. In case you have a website, the domain that you type to be able to open it is for your convenience, but the server where the site files are still has an IP. Considering that there're many more websites and devices than there're IP addresses, all of the shared web hosting servers have a number of sites under the same IP, while using a dedicated server you will have a dedicated IP too. Even in the first case though, you can acquire a dedicated IP for your websites and host them on a shared server. One benefit would be that you will enjoy far better search engine positions because a dedicated IP generally means a faster loading site. Also, you need such an IP when you want to purchase an SSL certificate for your website and shield the data that your visitors submit on it.