"Three-point lightingis a standard method used in visual media such as video, film, still photography and computer-generated imagery. By using three separate positions, the photographer can illuminate the shot's subject (such as a person) however desired, while also controlling (or eliminating entirely) the shading and shadows produced by direct lighting."
http://en.wikipedia.org/wiki/Three-point_lighting
3-point-lighting.gif
"The first light is a key light. Usually this is the strongest light and this light sets the lighting of the scene.
The second light is called a fill light, this light helps fill the shadows that the main light casts.
The last light is called a backlight (because it comes from the back), and is used to create a contour and separation. It is common to use a snootor a gridspot on the backlight to avoid a spill."
http://www.mediacollege.com/lighting/three-point/



3 point lighting tutorial


Three point lighting is when you light your subject from three different sources. This helps to balance the contrast and control the shadows.

Three Light Sources:
  • Key: This is the main light source. It shines directly on the subject, usually from the front-right or front-left. It provides the overall look and feel of the shot.
  • Fill: The fill provides balance to the key by filling in the rest of the subjects face with a softer light. It comes in from the front-side opposite the key light.
  • Back: The back light creates a nice rim of light around the back the subject, separating them from the background. It can also be called a "hairlight" or "rim-light".
How to Setup 3-Point Lighting:
  1. Start in the dark. Begin with all of your lights off, and as little other ambient light as possible. This will help you differentiate between the three lights that you will be adding.
  2. Add your key light. Your key light is the brightest light in the scene and creates the overall feel of the shot. Adjust its brightness to your liking. It's recommended to angle the key light about 30 degrees the right or the left of the subject. Another good tip is to have the key light nice and high, to reduce shadows on the face.
  3. Add your fill light. The fill light should be on the opposite side of the key, but still in the front. A good tip is to not make the key and fill symmetrical. The fill should be at face-level of the subject, and should fill in the remaining shadows. The intensity of the fill light should be about half of the key light.
  4. Add your back light. And finally, the back light will separate your subject from the background. It can be placed anywhere behind the subject, but make sure to not get it in the shot! You'll want to angle it down from pretty high, so as to achieve a nice outline on the edge of the subject.

Source: Niebauer, By Stephen. "3-Point Lighting on Vimeo Video School." Vimeo, Video Sharing For You. Web. 29 Aug. 2011. <http://vimeo.com/videoschool/lesson/44/3-point-lighting>.

Video: (for more information)
3 point lighting basics
Photo:
green-screen-lighting---3-point-lighting-diagram.gif
1) Refer to video for step by step.
2)


This method used in visual media such as video, film, still photography and computer-generated imagery. This is a simple skill but highly helpful when filming and such. Some might call this the key to lighting. Once you understand three point lighting you are well on the way to understanding all lighting.
The technique uses three lights called the key light, fill light and back light. Naturally you will need three lights to utilize the technique fully, but the principles are still important even if you only use one or two lights. As a rule:
  • If you only have one light, it becomes the key.
  • If you have 2 lights, one is the key and the other is either the fill or the backlight.

http://www.mediacollege.com/lighting/three-point/

This here is a simple discription and informational tutorial of three point lighting.

http://www.youtube.com/watch?v=LFM8bHuYmhg