If you've ever been on a film set one of the first pieces of advice that you are given is, "bring a book." There's alot of down time and reading a book helps while away the hours. Especially if you are background.
Background is just an industry term for being an extra...all those people in the background of a scene that you shouldn't be noticing. This background player has been seen on screen at a bar with a copy of Malcolm Lowry's Under the Volcano, riding the subway with a copy of Lao Tse and this past week walking a downtown street carrying Jeff Seymour's The Real Life Actor.
If you've acted before, Seymour's book will make you rethink your craft. If you are just starting out, The Real Life Actor will open your eyes.