Several different types of lights exist for use in stage lighting. The easiest to use are probably parcans, beam lights that are popular with traveling shows because they are lightweight and durable. The name parcan comes from the Parabolic Aluminized Reflector (PAR) lamp which provides the light, and the external casing, which is essentially a "can" (hence, "PAR can"). Other basic lights are scoops, which are flood lights; and fresnels (pronounced "frennel"), which have soft edges and are used mainly for color washes (blanketing an area with one color).
Other types of lights have more variable components. Ellipsoidal lights are very prevalent, and they have the ability to change focus, soften or sharpen edges, and change the shape or coverage of the lit area with shutters. Profile lights create a spot that can be manipulated with lenses to alter the hardness or create distinct shadows. One type of profile light is a followspot--as evidenced by the name, this spot follows an actor, sometimes using internal gels and shutters.
Color in lighting is created with gels, which are pieces of tinted plastic made to slide in front of lights. Unlike in art, the primary colors in light are red, blue, and green, but gels come in a variety of colors. Colored lighting has three variable aspects: hue, value, and saturation. Hue refers to the "color" of the light, such as red, green and blue. The value refers to the lightness or darkness of the color. Saturation refers to the purity or intensity of the color. Manipulation of these three factors can produce almost endless light possibilities.
Stage lighting can be angled in four basic directions: front, side, back and down. Front, side and back lighting refers to the direction from which the light comes, not the direction it goes. Therefore, front lighting is from the front of the stage, side lighting from the side of the stage, and back lighting from the back. Down lighting, however, does refer to light that is directed down, from lighting rigged above the stage. Angles can create levels and depth. Low lights create flatness in a scene, whereas high lights create shadows.
Brightness is the perception of light based on interaction between the eye, the object, and the intensity and illumination of the lighting. Intensity is the strength of lighting source (irrespective of distance or other factors), and illumination is the amount of light in an area. Brightness can be influenced by distance, reflectivity of objects and the size of a stage. Changes in intensity and illumination alter the brightness perceived by an audience.