An IP address is a unique number which identifies a website or a server on the Internet, so in the event that you have a dedicated IP, it shall be employed just by your sites and shall not be shared with others as it happens with shared Internet hosting accounts. Provided you have your own hosting server, you shall have a dedicated IP, but you may need extra ones for different purposes. If you have a web-based store, for example, you will need an SSL certificate for it, in order to make certain that the payment info which your clients submit will be encrypted and secure. The same is valid if you have a login form of some type and you want the usernames and the passwords that visitors input to be secured. The SSL certificate requires a dedicated IP address, which needs to be different from the one that you already have on the server. You could also need a separate IP for an application such as a VoIP server, or if you desire a slightly better overall performance for a certain Internet site, which shall influence its position in search engine results.