Wide Angle Lenses are the lens of choice for shooting expansive outdoors, and also for shooting interiors where the subject is very close to the camera and a large width of the subject is to be captured. For instance, for shooting an interior whiteboard video from close range, a moderate wide lens can be used.
Extreme wide lenses can cause lines to distort - straight lines can appear curved when shot from close up with an extreme wide lens, an effect called the barrel distortion. Moderate wide lenses can however be artistically used to give a greater perception of depth to the image. This is because when shot from a wide angle lens, the subject is significantly magnified compared to the background.
Any lens with a focal length of less than 35mm is considered a wide angle lens. The shorter the focal length, the greater would be the field of view of the lens being used. Extreme wide angle lens are available at focal lengths of 24mm, 21mm, 17mm and 14mm.