I will answer this question from the UK perspective, because in the US there is different standard terminology and someone like BillNutt will fill you in on the US parlance.
The area that you come into when you first enter the theatre is called the Foyer, there may also be a Box Office are and potentially and possible (because it raises more money than the theatre itself) a bar or/and a restaurant/cafe. Then we move into the auditorium, where the seats are. There are rows of seats on many levels. The very top is called The Gods or the Balcony, the second from top is called The Upper Circle, the top is called the Dress Circle, the bottom on the ground leading from the doors out to the stage is called the stalls. All of this area is known as 'Front of House' and is supervised by a Front of House (or FOH) Manager or a House Manager.
The area that you come into when you first enter the theatre is called the Foyer, there may also be a Box Office are and potentially and possible (because it raises more money than the theatre itself) a bar or/and a restaurant/cafe. Then we move into the auditorium, where the seats are. There are rows of seats on many levels. The very top is called The Gods or the Balcony, the second from top is called The Upper Circle, the top is called the Dress Circle, the bottom on the ground leading from the doors out to the stage is called the stalls. All of this area is known as 'Front of House' and is supervised by a Front of House (or FOH) Manager or a House Manager.