An IP address is a unique number that identifies a site or a server on the Internet, so if you have a dedicated IP, it shall be employed just by your websites and will not be shared with other individuals as it happens with shared website hosting accounts. Provided you have your own hosting server, you will have a dedicated IP, but you may require additional ones for a variety of uses. If you have an Internet store, for instance, you will need an SSL certificate for it, to ensure that the payment information which your clients submit shall be encrypted and safe. The same is valid in case you have a login form of some kind and you would like the usernames and the passwords that visitors input to be protected. The SSL certificate requires a dedicated IP address, which needs to be different from the one that you already have on the server. You may also need an individual IP for an application such as a VoIP server, or if you would like a slightly better performance for a given website, which will affect its position in search engine results.