The basic rule is that, besides the entry door, there has to be one other exit that opens to the outside, which can be another door, but is usually a window. There are size rules for the window.
The window is intended not just for entry of firefighters, but also for unassisted exit.
In some older apartment buildings (eg, Portland, OR), the fire egress plan involves other residents being able to break into your apartment and exit using your external fire escape.
In these buildings, you'll see an apartment on each floor with a glass window in their door, and a heavy object hanging from a chain next to it. (It's a fun puzzle for guests -- "See that bolt hanging from the chain? See the adjustable crescent wrench on the next floor? How does that work?")
Wow, that's messed up. Might as well have a big "burglary decoy" sign above that door too. Something makes me think letting agents have trouble getting the same price for that flat...
This is quite false. The ability to use a bedroom window as an emergency exit is required by typical US building codes (e.g., http://www.bobvila.com/articles/406-what-makes-a-room-a-bedr...).
The basic rule is that, besides the entry door, there has to be one other exit that opens to the outside, which can be another door, but is usually a window. There are size rules for the window.
The window is intended not just for entry of firefighters, but also for unassisted exit.