An IP address is a unique number which identifies a site or a hosting server on the Internet, so in the event that you have a dedicated IP, it shall be employed solely by your Internet sites and will not be shared with other people as it happens with shared web 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. In case you have a web-based store, for example, you shall need an SSL certificate for it, to make sure that the payment information that your clients submit shall be encrypted and secure. The same is valid in case you have a login form of some type and you wish the usernames and the passwords which visitors input to be secured. The SSL certificate requires a dedicated IP address, which has to be different from the one which you already have on the web server. You might also need an independent IP for an application such as a VoIP server, or if you desire a slightly better performance for a given site, which may affect its position in search engine results.