All devices on the Web are identified by a specific number called an IP address, for example 123.123.123.123. When you have a website, the domain name that you type to be able to open it is for your convenience, yet the server where the website files are still has an IP address. Due to the fact that there're many more sites and devices than there're IPs, all of the shared website hosting servers have a number of websites under an identical IP, whereas using a dedicated server you will have a dedicated IP as well. 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'll enjoy far better search engine positions because a dedicated IP generally means a faster loading website. In addition, you need such an IP if you would like to get an SSL certificate for your site and shield the data that your visitors submit on it.