What do you call this thing? 10 points =)?

a href="http://hookedonhouses.net/wp-content/uploads/2008/11/nathandr.jpg" rel="nofollow"http://hookedonhouses.net/wp-content/upl…/a that painting, what do you call the paper or whatever the paint's painted on, what do you call it? because i'm also thinking about doing a DIY painting only problem is i don't know what it's called all i know is that the thing is stapled at the back on the wooden frame, oh geez this is a stupid question but i need n answer to put me to sleep.