A pipe organ is a musical instrument that produces sound by air vibrations created in an organ pipe, which is controlled by a musician from a keyboard.  The pipe organ produces one tone at one pitch; a given pipe is not mechanically manipulated in some way to produce multiple notes like a flute or guitar string.  Since there is just one pipe for each note, a keyboard with 61 notes (5 octaves) would have 61 pipes, one for each note.  The one set of pipes for each note on the keyboard makes just one kind of sound. The organ will have several sets of pipes; each of these sets of pipes is called a "rank," which can make different sounds.  This is similar to an orchestra which has many different types of instruments, each having its own characteristic sound.  If a keyboard of 61 notes controls a group of 10 ranks of pipes, there will be 610 pipes playable from that keyboard.  There are many more pipes in an organ than the ones you typically see.  The pipes are arranged on a windchest which is enclosed on the sides and back by a case so that the sound projects out the front more clearly.

The Casavant Frères pipe organ at St. Luke Lutheran Church has twenty-six ranks of pipes spread over three divisions.  (A rank of pipes is composed of one pipe for each key on the keyboard or pedal board all of which produce the same type or color of sound, e.g. a flute or oboe, etc.)  The organ has more than 1500 pipes.  The console of Opus 3776 has two manuals (keyboard) with a compass of 61 notes each and a pedal keyboard of 32 notes.  Each of the two keyboards corresponds with and is dedicated to playing the pipes found in two or three divisions, with the notes of the pedal division played by the feet.  The names of the divisions are Great, Swell, and Pedal.

Great:  This is the main division of the organ.  It contains the primary "organ sounding" stops of the instrument and is used for hymn singing, forte accompaniments and solo organ repertoire.  The pipes of this division are placed in the top right chamber of the organ and are played by the lower keyboard on the console.

Swell:  The upper keyboard plays the pipes of the Swell division.  The swell gets its name from the fact that all the pipes of this division are contained in a box with "swell shades" much like large plantation shutters that are opened and closed by means of a pedal at the console, allowing the organist to manipulate the volume of the pipes for musical expression.  The Swell division is placed in the upper left chamber of the organ with softer stops in the front and louder stops in the rear.

Pedal:  The Pedal division contains some of the lowest sounding pipes in the organ and is used more frequently to play the bass line.  This division contains three stops of its own, but many more stops from the other divisions are also playable from the pedal keyboard making it very versatile.