The pipe organ is often called the 'King of Instruments' due to its massive size and sonic range. A single organ can have thousands of pipes, organized into 'ranks.' A rank is a complete set of pipes that all produce the same type of sound (e.g., flutes, trumpets, or strings) but at different pitches. When an organist pulls a 'stop,' they are engaging or disengaging a specific rank of pipes. The largest pipe in a rank determines the pitch; a '16-foot stop' produces a sound an octave lower than an '8-foot stop.' The pipes themselves fall into two categories: 'flue pipes,' which work like a recorder by blowing air across an edge, and 'reed pipes,' which contain a vibrating metal tongue. The complexity of the 'action'—the mechanism connecting keys to pipes—has evolved from mechanical wooden trackers to modern electric and digital systems.