All devices on the Web are identified by a unique number called an IP address, for example 188.8.131.52. When you have a website, the domain that you type in order to load it is to save you time, but the server where your website files are still has an IP address. Considering that there're a lot more sites and devices than there are IPs, all of the shared website hosting servers have a number of websites under the same IP, whereas using a dedicated server you'll get a dedicated IP as well. Even in the first case though, you'll be able to get a dedicated IP for your websites and host them on a shared server. One benefit would be that you may enjoy superior search engine positions because a dedicated IP generally means a quicker loading site. What's more, you need such an IP in case you would like to purchase an SSL certificate for your site and protect the info that your visitors submit on it.