All devices on the Web are recognized by a specific number called an IP address, for instance 18.104.22.168. In case you have a website, the domain that you type in order to access it is to save you time, but the server where your site files are still has an IP address. Since there're a lot more sites and devices than there're IP addresses, all shared website hosting servers have a number of websites under the very same IP, while when you use a dedicated server you'll get a dedicated IP too. Even in the first case though, you're able to acquire a dedicated IP for your sites and host them on a shared server. One benefit would be that you'll have superior search engine positions since a dedicated IP generally means a quicker loading website. What is more, you need such an IP when you want to obtain an SSL certificate for your website and protect the information that your visitors submit on it.