If you host a site on a server, it uses the server's shared IP - an exclusive number that's used to identify any device connected to the Web. The domain name which you use for the site is for quick access and convenience of the site visitors, but on a lower level, their web browser connects to the IP of the server. As there're far more sites than IP addresses, shared website hosting servers use the same IP for multiple websites even if they belong to several users. Even though this doesn't affect the site performance directly, having a dedicated IP can slightly enhance the loading speed of a particular website, giving it higher positions in search engine results. Such an IP is needed for the installation of an SSL certificate too, so when you plan to protect the payment or login data that your website visitors submit, you'll need an IP in addition to the SSL.