The apron is any part of the stage that extends past the proscenium arch and into the audience or seating area. The Elizabethan stage, which was a raised platform with the audience on three sides, is the outstanding example.
Most stages edges are curved slightly outward providing a very small apron. Some have a large playing space protruding into the audience and in turn a very large apron.
The Globe has a rectangular stage platform, also known as an 'apron stage', thrust out into the middle of the open-air yard. The stage measured approximately 43 feet (13.1 m) in width, 27 feet (8.2 m) in depth and was raised about 5 feet (1.5 m) off the ground. On this stage, there was a trap door for use by performers to enter from the "cellarage" area beneath the stage.
An apron stage can also be another name for a thrust stage.