An IP address is a unique number which distinguishes a site or a web server on the world-wide web, so if you have a dedicated IP, it will be used just by your websites and won't be shared with other individuals as it happens with shared Internet hosting accounts. In case you have your own server, you'll have a dedicated IP, but you may need extra ones for various purposes. Provided you have an Internet store, for example, you shall need an SSL certificate for it, so as to ensure that the payment information that your clients submit will be encrypted and safe. The same is valid in the event that you have a login form of some sort and you want the usernames and the passwords that visitors type in to be protected. The SSL certificate requires a dedicated IP address, which has to be different from the one that you already have on the server. You could also need an independent IP for an app such as a VoIP server, or if you would like a slightly better efficiency for a particular Internet site, which may affect its position in search engine results.