Why would I want to put information on my web page that is not visible to the typical viewer?
It is useful to have information that is not visible to the viewer because you can add notes on your webpage that the user cannot see. For example if you wanted to change the color of the webpage later but you still wanted the website to be shown you could add a note that tells you that you are supposed to change the color of the webpage.
Meta data is needed so that the browser can work properly. You can use it so that web browsers no what your page is about. For example if someone searches for computers and your page is about computers then you can use meta data so that the viewer will come to your page