An IP address is a unique number which separates an Internet site or a server on the world-wide web, so if you have a dedicated IP, it will be employed solely by your sites and shall not be shared with other individuals as it happens with shared web hosting accounts. If you have your own server, you shall have a dedicated IP, but you may require additional ones for many different uses. If you have an online store, for instance, you'll need an SSL certificate for it, in order to ensure that the payment info which your customers submit will be encrypted and protected. The same is valid in the event that you have a login form of some sort and you want the usernames and the passwords which visitors input to be protected. The SSL certificate requires a dedicated IP, which needs to be different from the one that you already have on the hosting server. You could also need a separate IP for an application such as a VoIP server, or if you would like a slightly better functionality for a given website, which may affect its position in search engine results.