All devices on the Web are identified by a unique number called an IP address, for example 220.127.116.11. When you have a website, the domain that you type to be able to open it is for your convenience, however the server where your site files are still has an IP address. As there are far more websites and devices than there are IP addresses, all the shared web hosting servers have a number of sites under an identical IP, whereas when you use a dedicated server you'll have a dedicated IP too. 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 may enjoy far better search engine positions since a dedicated IP generally means a faster loading site. What's more, you need such an IP in case you would like to acquire an SSL certificate for your website and protect the info that your visitors submit on it.