An IP address is a unique number that 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 just by your Internet sites and will not be shared with other individuals as it happens with shared hosting accounts. If you have your own hosting server, you will have a dedicated IP, but you may require extra ones for different purposes. In case you have an online store, for instance, you will need an SSL certificate for it, to make certain that the payment info your customers submit will be encrypted and safe. The same is valid in case you have a login form of some type and you want the usernames and the passwords which visitors input to be protected. The SSL certificate requires a dedicated IP, which should be different from the one that you already have on the hosting server. You may also need an individual IP for an application such as a VoIP server, or if you desire a slightly better performance for a certain Internet site, which shall affect its position in search engine results.