An IP address is a unique number which separates an Internet site or a hosting server on the Internet, so in the event that you have a dedicated IP, it'll be used exclusively by your sites and shall not be shared with others as it happens with shared Internet hosting accounts. In case you have your own web server, you'll have a dedicated IP, but you may require extra ones for many different uses. Provided you have an online store, for instance, you shall need an SSL certificate for it, so as to make certain that the payment information which your clients submit will be encrypted and protected. The same is valid in case you have a login form of some kind and you wish the usernames and the passwords that visitors input to be protected. The SSL certificate requires a dedicated IP address, which has to be different from the one which you already have on the server. You could also need an individual IP for an application such as a VoIP server, or if you want a slightly better functionality for a particular Internet site, which shall influence its position in search engine results.