One thing you will learn about a craft, hoppy or job is that they all have their own language. Theatre has terms that give relevance to the nature of the business. First lets start with the wings: the wings are the right and left leaving areas of the stage. Most wings have hanging curtains that hide the actors exiting or entering from stage right or left. Next lets focus on the greenroom: the greenroom is the room where the actors gather before they are set to enter on stage. Depending on the theatre, every greenroom is different, some still use the traditional green color which originated in London theatre. Another term you may hear a lot of in theatre and entertainment is acoustics, this refers to how the sound quality is within the theatre or area where the entertainment is presented. The acoustics can depend on the size, walls or even the type of material used on stage. It's also important to note that the section where the audience is seated is known as the house. This area, in some theatres, is sometimes used in the production to allow the characters to bring the audience off stage and into the action.
For more theatre terms visit: http://teachers.oakarts.org/~mberry/Theatre+Vocabulary+List