An IP address is a unique number that distinguishes an Internet site or a web server on the world-wide web, so if you have a dedicated IP, it'll be employed exclusively by your Internet sites and shall not be shared with other people as it happens with shared Internet hosting accounts. Provided you have your own web server, you'll have a dedicated IP, but you may need additional ones for many different purposes. Provided you have an online store, for example, you will need an SSL certificate for it, in order to ensure that the payment info that your customers submit will be encrypted and safe. The same is valid if you have a login form of some sort and you want the usernames and the passwords which visitors enter to be secured. The SSL certificate requires a dedicated IP address, which ought to be different from the one that you already have on the machine. You might also need an independent IP for an application such as a VoIP server, or if you need a slightly better overall performance for a particular Internet site, which will affect its position in search engine results.