All devices on the Internet are recognized by a special number called an IP address, such as 123.123.123.123. In case you have a website, the domain that you type to be able to load it is for your convenience, yet the server where the website files are still has an IP address. Considering that there're many more websites and devices than there're IP addresses, all shared hosting servers have a number of websites under the same IP, whereas with a dedicated server you will have a dedicated IP as well. Even in the first case though, you can get a dedicated IP for your sites and host them on a shared server. One benefit would be that you may get far better search engine rankings because a dedicated IP often means a faster loading website. Last but not least, you need such an IP in case you want to obtain an SSL certificate for your website and protect the information that visitors submit on it.