The GQ:Why would I want to put information on my web page that is not visible to the typical viewer?
Information about the web page that is not necessary for the average viewer to see would only be put in the coding and not visible for others. Metadata is one example. Metadata describes what language the page will be in, who the author is, a description of the page, and how it is viewed on different devices. This information is sent to the browser to tell it some parameters about the page.