I realize that a "dark" show means that it's closed temporarily, but it seems to me to be an odd way to say that. There must be more to it.
[Editor's Note: The answer to this question ran originally in 2005. It's so good -- written by Jessica, the QoDmother for many many years -- that we remembered it and are happy to rerun it here.]
What is a dark show?
A dark show was written by someone with a sick sense of humor, features macabre and disturbing costuming, and should be avoided by those prone to nightmares.
Just kidding, of course (although we have seen some shows like that).
In the context of shows, "dark" is actually a term that dates back to Elizabethan times. It's used throughout the theatre world to indicate that a venue is closed to the public, since no lights means no show; i.e., the theater is literally in darkness.
Some theaters go dark for a prolonged period of time after one show has completed its run and while the next show is in preparation. Sometimes "dark" refers to the night before an opening when no rehearsal is scheduled. In Las Vegas, where the same show can run year after year, "dark" usually refers to a regularly scheduled day of the week (or certain whole weeks during the year) when there’s no show, enabling cast and crew to have a well-earned night or week off.
An interesting aside is that when some theaters are dark, a single light is left burning, usually center stage, and is known as the "ghost light." The origins of this tradition are somewhat hazy and range from the highly apocryphal-sounding story that a burglar once fell off the stage in the dark, broke his legs, and successfully sued the theater, to the fact that it’s an early Equity rule dictating that a light had to be present during rehearsals so that the pianist could see what he/she was playing and the producer didn’t have to call an IATSE crew just for rehearsals.
The more romantic version is that it’s either there to keep at bay the ghosts of past performances or to keep the resident theater ghost company overnight, since if all the lights go out, it will think it’s been abandoned and cause accidents to happen on the set. This last explanation seems to be the most likely original reason, and not only explains the name, but also why so many theaters burned down in Shakespearean times, since the only available lighting then was candles -- somewhat hazardous in an era when theaters were made entirely of wood.