An IP address is a unique number that distinguishes a website or a server on the world-wide web, so in the event that you have a dedicated IP, it'll be used only by your Internet sites and shall not be shared with other people as it happens with shared website hosting accounts. If you have your own hosting server, you'll have a dedicated IP, but you may need additional ones for a variety of purposes. If you have an electronic store, for example, you will need an SSL certificate for it, so as to ensure that the payment info which your clients submit shall be encrypted and safe. The same is valid in the event that you have a login form of some sort and you wish the usernames and the passwords that visitors type in 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 hosting server. You could also need a separate IP for an application such as a VoIP server, or if you would like a slightly better functionality for a certain Internet site, which will influence its position in search engine results.