Actor - A person who performs as a character in a play or musical.

Author - A writer of a play (also known as a playwright) or a musical.  A musical's author include the book writer, the composer and the lyricist.  

Blocking - The actors' movement in a play or musical, not including the choreography.  The director usually assigns blocks during rehearsals.

Book Writer - One of the authors of a musical.  The book writer writes the lines (dialogue) and the stage directions.  Also called the librettist.

Cast - The performers in a show

Cheating Out - Turning oneself slightly toward the house when performing so the audience may better see one's face and hear one's lines.

Choreographer - A person who creates and teaches the dance numbers in a musical.

Composer - A person who writes the music for a musical.  

Creative Team - The author(s), director, choreographer, music director and designers for a play or musical.  

Cross - An actor's movement to a new position on the stage.

Dialogue - A conversation between two or more characters.

Director - A person who provides the artistic vision, coordinates the creative elements and stages the play.

Downstage - The portion of the stage closest to the audience.  The opposite of upstage.

House The area of the theater where the audience sits to watch the show.

House Left - The left side of the theater from the audience's perspective.  If something is located "house left,"  it is located to the left side of the audience as they are seated in the theater. 

House Right - The right side of the theater from the audience's perspective.  If something is located "house right,"  it is located to the right side of the audience as they are seated in the theater. 

Lines - The dialogue spoken by the actors

Lyricist - A person who writes the lyrics of a musical.  The lyricist works with a composer to create songs.

Lyrics - The words of a song

Monologue - A large block of lines spoken by a single character.  When spoken alone onstage or directly to an audience, a monologue reveals the inner thoughts of the character.  

Music Director - A person who is in charge of teaching the songs to the cast and orchestra and maintaining the quality of the performed score.  

Musical - A play with songs that are used to tell a story. 

Off-Book - The actors ability to perform his or her memorized lines with out holding the script.

Onstage - Anything on the stage and within view of the audience.  

Opening Night - The first official performance of the production, after which the show is frozen, meaning no further changes are made. 

Play - A type of dramatic writing meant to be performed live on a stage.  A musical is one kind of a play.  

Protagonist - the main character or hero of a play. 

Raked Stage - A stage that is raised slightly upstage so that it slants towards the audience.

Rehearsal - A meeting during which the cast learns and practices the show. 

Script - The written words that make up a show, including dialogue, stage directions and lyrics.  Also meaning the Book that contains those words.  

Stage Directions - Words in the script that describe the actions for the characters. 

Stage Left - The left side of the stage, from the actor's perspective.  The same side of the theater as house right.  

Stage Manager - A person responsible for keeping all rehearsals and performances organized and on schedule, and for calling sound and light cues during the performance. 

Stage Right - The right side of the stage, from the actor's perspective.  The same side of the theater as house left

Upstage - The part of the stage furthest from the audience. 

Warm-Up - Exercises at the beginning of a rehearsal or before a performance that prepare actors' voices and bodies.