Stalls - an area of upstairs seats.
aisle - a way down from back to front between seats.
circle - an area of downstairs seats.
dressing room - where actors put on their costumes and makeup.
stage - the area on which the performance takes place
box office - the place where you go or phone to buy tickets.
row - .a line of seats
backstage - the whole area out of sight of the audience.
box - a little private balcony with 3-5 seats only.
foyer - the theatre entrance hall where people meet before going in.