An IP address is a unique number which separates a website or a server on the Internet, so in the event that you have a dedicated IP, it'll be used exclusively by your sites and won't be shared with other individuals as it happens with shared Internet hosting accounts. In case you have your own hosting server, you'll have a dedicated IP, but you may require additional ones for various purposes. Provided you have a web-based store, for instance, you shall need an SSL certificate for it, to make certain that the payment information which your customers submit shall be encrypted and protected. The same is valid if you have a login form of some sort and you want the usernames and the passwords that visitors type in to be protected. The SSL certificate requires a dedicated IP address, which ought to be different from the one that you already have on the hosting server. You could also need an independent IP for an application such as a VoIP server, or if you desire a slightly better efficiency for a given site, which shall affect its position in search engine results.