A stall is where the wing loses lift due to a high angle of attack (usually because you're too slow for the wing to fly at the G loading you're asking it to maintain); if aggravated the airplane can roll (largely due to asymmetric lift, yawing moments, and loss of control effectiveness. An airplane usually loses control effectiveness in the order of ailerons, elevator, and rudder and they come back in reverse order. Also, one side of the wing might reach a stall AOA before the other adding a rolling moment). Pilots train to stall characteristics and recovery on lighter aircraft and it's a basic skill of handling. Larger airplanes aren't typically stalled (due to undesirable characteristics around the stall). But understanding stall recovery and high AOA maneuvering is a very basic part of becoming and being a pilot. It becomes especially important in fighters because maneuvering here max performs the airplane and can be the difference between winning and losing a close in fight. Several commercial aircraft (and many lighter ones) have been lost due to improper action during the stall (you need to unload--push or relax pressure forward to unload the wing and get it flying again while adding thrust). If you pull back instead the airplane can go into some pretty impressive post-stall gyrations. I stumbled across this on the internet and found it fascinating (it appears to be a flight test of the 717--a small-ish to medium size airliner about the same size as the older DC-9s). What struck me is the rate at which the airplane rolled (this is an airliner rolling over--rather quickly--while test pilots were trying to address some potential dodgy stall characteristics). The nose pitches down alot more than I'd personally want (once the wing gets flying it's better to roll to the nearest horizon--even if you're inverted--rather than let the nose get buried too far--but you ALSO have to make sure the wing's flying and your control inputs won't further aggravate the stall) -- but they're the ones who would have known the flight characteristics and airplane much better than I. And were actually there. A bunch of warning horns are going off; they're at medium altitude so you can ignore the 'Altitude' one. But the clacker and apparent 'overspeed' one would get my attention in that you have to be very careful when pulling that you don't break the jet. Interesting ride. If the sim is to be believed, the 777 has excellent and relatively straightforward stall characteristics and I've never seen it do anything like this. Then again, I'm not sure how accurately the computer tapes replicate what the airplane actually would do at high AOA. (the lever on the left side of the throttles the left seat pilot pulls and the right seat pilot re-stows after the event are the speed brakes which were used to apparently mitigate the overspeed event that happened as the nose pitched downward quite a bit after the roll).