An IP address is a unique number that identifies a website or a web server on the world-wide web, so if you have a dedicated IP, it will be employed just by your sites and won't be shared with other people 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 need extra ones for various uses. Provided you have an electronic store, for example, you'll need an SSL certificate for it, to make certain that the payment information which your clients submit shall be encrypted and secure. The same is valid if you have a login form of some sort and you would like the usernames and the passwords which visitors input to be secured. The SSL certificate requires a dedicated IP address, which has to be different from the one that you already have on the machine. You may also need an individual IP for an app such as a VoIP server, or if you need a slightly better efficiency for a certain Internet site, which may influence its position in search engine results.