Lighting designs are created on paper before they are realized inside the theater. The "light plot" is the primary component of this paper work. It is a scale drawing of where every light will be placed with notations about each light's color, focus and how it is controlled through the power system. Additional paperwork may include a spreadsheet called an "instrument schedule," which notes the placement, color, focus and control of each light, plus additional information such as the light's wattage and whether it is grouped with other lights, organized by each light's placement within the theater. Designers may also use a "magic sheet", which identifies lights by group, such as face light, back light, side light, etc., in the order they appear on the control board. A "channel list" offers the same groupings as a magic sheet but is printed in spreadsheet format and includes the same information as the instrument schedule, just in a different order.
Lighting systems consist of "instruments," "circuits," "dimmers," "channels" and a "console" or "light board." Each light plugs into a circuit, which can be thought of as similar to a household wall outlet. That circuit is controlled by a dimmer, which directs the amount of power flowing to the light. That dimmer is controlled by a channel on the light board. The channel allows an operator to send a signal to the dimmer telling it how much power to let through, while the light board provides a central place through which all dimmers are controlled. In some theaters, each circuit has its own dimmer, called a "dimmer per circuit" layout. Older theaters sometimes have each channel permanently assigned to control a specific dimmer, which may in turn control several circuits. This is known as a "dimmer per channel" layout. Circuits have numbers or letters to identify them, while channels are numbered. Electricians generally do not interact directly with the dimmers in most venues.
Several types of lighting instruments are available in the theater. "Wash" instruments provide broad, general light that is only slightly controlled by adjustments on the instrument. "Profile" fixtures have highly controllable beams that can be shaped or set to project patterns of light. Standard parts of lighting instruments include "reflectors," which direct and shape the beam of light, "lamps," which are the actual glass-and-filament bulbs or tubes that produce the light and "lenses," which are shaped glass objects the light shines through and that further control the beam. Profile style instruments also generally have "barrels," denoting the cylindrical front part of the fixture that is used to adjust the sharpness of the beam edge.
Accessories for lighting instruments can add color, motion and other effects to the light. Color can come from acetate sheets called "color filters" or "gels," or from glass inserts that may be placed in front of the lamp or in place of the lens. Patterns are often called "gobos," short for "go-between" because they are placed between the lamp and the lens. They may be printed glass or cut steel, and the pattern on them blocks portions of the light and projects a pattern in the beam. Both gobos and gels require holders, often called "frames."