what is :media in application layout in .js and .css include tag???

rubyonrails-talk
1 
    <%= stylesheet_link_tag "components/jscrollpane/jscrollpane.css", :media=>"screen" %>

	<%= stylesheet_link_tag "components/tipsy/tipsy.css", :media=>"all" %>

what is this :media?

and what is the this “all” and “screen”

if there are more than “screen” and “all” in media tag than explain it also…

thanks

Fahim Babar Patel

2

Googling for stylesheet media screen brings up this as the first link http://www.w3.org/TR/CSS2/media.html

Colin