Console
The large unit where the organist sits to play and control the organ. This includes the keyboard or manuals, pedal board, pistons, and drawknobs or stops.
Division
The pipes are grouped into several separate sections called divisions such as the Great, Swell, Solo, Positive, and Pedal. Each is controlled by its own manual or the pedal board.
Electric Key Action
In an electric key action, a wire, an electric circuit, and an electro-magnet cause the valve below each pipe to open and close. When you press the key, you close an electrical contact. Electricity flows to the circuit that causes an electro-magnet to open and close the valves under each pipe.
Mechanical Action (Tracker Action)
The key is connected to trackers (wooden, metal, or plastic strips or rods) that eventually connect to the valves that open to admit air from the wind chest into the pipe. When you press the key, you are physically opening the valve in the wind chest. In mechanical action, there is one valve for each note on the keyboard.
Note: The Verizon Hall organ has both electric and mechanical key action.
Pipes
Organ pipes fall into one of four broad sound categories: principal, flute, string, and reed. The first three types are known as "flue" pipes and work like whistles. The majority of organ pipes are flue pipes. In contrast to the whistle-like flue pipes, the reed pipes work like clarinets or saxophones, but have a brass "tongue" instead of a cane reed. Some of the reed pipes are the loudest pipes in the organ.
Rank
A rank is a row of pipes all of which make the same sound, but at different pitches. For example, all the pipes for a Spire Flute (one kind of flute sound) will be in the same row. Organs are often described by the number of ranks they have. A 60 rank instrument is a fairly large size while an 18 rank instrument is small. The Verizon Hall organ has 125 ranks.
Reservoir
This is a spring-loaded, expandable box for storing wind. Weights and springs are used on the expandable part to keep the air under a constant pressure. If the wind going to the pipes is not under the same, constant pressure, the sound will waver.
Stop
A sound represented by a knob at the organ console. A stop generally plays one rank of pipes, but some stops called 'mixtures' have two or more ranks, meaning that two or more pipes play from each key.
Swell Shades
Slats that look like Venetian blinds that can be opened and closed through a pedal called the swell shoe. Opening or closing the swell shades controls the loudness of the sound.
Windchest
The pipes sit on top of this very specially constructed wooden box. When a stop is on, air flows from the wind reservoir into the chest. When notes are played, it uses the air from the chest to make the pipes speak.