An IP address is a unique number that identifies a site or a server on the Internet, so in the event that you have a dedicated IP, it will be employed only by your websites and will not be shared with others as it happens with shared Internet hosting accounts. In case you have your own hosting server, you will have a dedicated IP, but you may require additional ones for various uses. If you have an electronic store, for example, you will need an SSL certificate for it, in order to ensure that the payment info which your customers submit will be encrypted and safe. 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 has to be different from the one that you already have on the server. You might also need a separate IP for an application such as a VoIP server, or if you desire a slightly better overall performance for a particular Internet site, which will affect its position in search engine results.