What is the term for a system of ropes and pulleys used to raise and lower scenery and lighting from the stage?

The term for a system of ropes and pulleys designed for the purpose of raising and lowering scenery and lighting on stage is commonly referred to as the fly system. This mechanism is integral to theatrical productions, as it allows for seamless transitions between different scene settings and the manipulation of lighting fixtures without disrupting the performance.

The fly system operates by using a series of lines (ropes), pulleys, and weights that work together to create a counterbalanced system. When a stagehand pulls on a rope, the counterweights enable heavy pieces of scenery or lighting to be lifted or lowered with relative ease, ensuring safety and efficiency during performances.

In contrast, while the grid system serves as a structural framework above the stage to support the fly system, it does not specifically refer to the mechanism of movement. Scenery control and lighting rig are terms that pertain to specific elements of stagecraft but do not encompass the full functionality characteristic of the fly system. Thus, the fly system is the correct answer as it most accurately describes the entire mechanism utilized for this purpose in stage productions.