An IP address is a unique number which distinguishes a website or a web server on the world-wide web, so in the event that you have a dedicated IP, it shall be used only by your websites and will not be shared with others as it happens with shared web hosting accounts. In case you have your own hosting server, you shall have a dedicated IP, but you may require extra ones for various uses. In case you have a web-based store, for instance, you shall need an SSL certificate for it, in order to ensure that the payment information which your customers submit will be encrypted and protected. 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 input to be secured. The SSL certificate requires a dedicated IP address, which ought to be different from the one which you already have on the machine. You might also need an independent IP for an app such as a VoIP server, or if you desire a slightly better functionality for a certain website, which will influence its position in search engine results.