howard01

As posted by others before me, lots of things happen after the doors closed and the aircraft is pushed back from the gate. Obviously, the tug has to be disconnected, the engines started and the AUP has to be disconnected. You will hear all sorts of noises and cabin lights will flicker one or more times. The pilot/co-pilot has to contact the tower for taxi instructions. The cabin attendants need to start/do their flight safety video and demonstration. ALL of this is normal and takes 3 or 4 minutes. Sometimes, the weather and congested airways or destination airports will cause your aircraft to taxi to a parking spot (aka holding pad or penalty box) to wait for the assigned slot for takeoff. These delays can be of any length of time starting at 10 minutes or it could be longer. Sometimes you may hear the engines being shutdown to conserve fuel if the wait will be longer.
Tip: If you fly on United, tune into channel 9 (on most of their aircraft) to listen to the pilot interact with Air traffic control about your flight.