An auditorium is the area within a theatre, concert hall or other performance space where the audience is located in order to hear and watch the performance.

The term is taken from the Greek auditorium which was a series of semi-circular seating shelves in the amphitheatre, divided by broad 'belts', called diazomata, with eleven rows of seats between each.

The audience in a modern theatre are usually separated from the performers by the proscenium arch, and comprises a lower flat area known as the 'stalls' or 'arena' and a number of rows of seats at opposite the stage and sometimes at the sides, known as 'boxes' or 'galleries'. The price to use seats in each part of the auditorium usually varies by the quality of the view of the stage.

In a church the auditorium is the nave, where hearers stood to be instructed.

In a monastery the auditorium is an apartment for the reception of strangers.