Three Point Lighting
Key Light
The Key Light is the main and most obvious source of light. It would be something like a lamp, candle, light or other source that can be seen in the shot to make the viewer think that's the main source of light, the one that is lighting the scene.
Filler Light
The Filler Light is the secondary source, usually placed behind the camera or the opposite side the the Key Light to eliminate shadows, like that on an actor's face if the light creates shadow.
Back Light
The Back Light is the support source, like a window or open door to a brighter room/exterior. This is mainly used to add a three dimensional effect, like making the background look a distance from the object to show depth of a scene.
Reflectors
Reflectors are used to reflect light at a subject, such as further eliminating shadows on a character's face, and can make certain points brighter and stand out more. They are in different sizes, which alter the amount of light reflected and how large the area lighted is, and are circular. They're packed in small round bags and open up when used.
Above: Class' 2-point lighting tutorial video
