I'm sure some of you have seen the following:
<link rel="stylesheet" src="styles.css" media="screen,projection" />
<link rel="stylesheet" src="styles.css" media="print" />
w3 can explain it best.
The media types are about what media is to be used to view the page.
If someone is printing the page, the
Screen is what you would normally think about - the computer screen, how most people will see the site.
Projection - if you want to have a larger font when projecting the website.