Off-Broadwayplays or musicals are performed in New York City. "Off Broadway" originally referred to the location of a venue (and its productions) on a street in Manhattan's Theater District that intersected the street called Broadway—the long-time hub of the theater industry in the United States. Now, generally speaking, the term refers to a professional venue in New York City whose seating capacity is between 99 and 500, or to a specific production that first appeared in such a venue.1
The rationale behind the designation is based on the implication that an Off-Broadway production is smaller and less fancy—in terms of venue size, star billing, writers'/choreographers' credentials, production cost, etc.—than a "Broadway" production.
There was a time when, regardless of the size of the venue, a theatre could not be considered Off Broadway if it were within the "Broadway Box" (the traditional Broadway Theatre District). This is no longer the case as evidenced by a number of theatres in that area, including (but not limited to) New World Stages, The Little Shubert Theatre and The Snapple Center. However, if an Off-Broadway theatre is located within the "Broadway Box," then there is a slightly higher minimum salary requirement for actors, according to Actors' Equity (labor union for live-theater performers) rules. 2
^ League of Off-Broadway Theatres and Producers. Inc. & The Association of Theatrical Press Agents and Managers. "Off-Broadway Minimum Basic Agreement". Retrieved on 2007-12-14.