Pan & Scan
Pan & Scan is a method used a lot by movie studios to create 4:3 versions of movies recorded in widescreen format by cropping out areas of the frames so that they have a perfect fit block for a 4:3 TV. The areas of the video that are cropped depend on where the action is currently.
Pan & Scan has a bad reputation among movie enthusiasts who claim that the movies are shot in widescreen format and should be viewed the way the director intended.
A Pan and Scan can also remove remove up to 45 percent of the original image (on 2.35:1 films) sometimes removing important background events.
Now with the growing popularity of HDTVs films are being panned and scanned at 1.78:1 instead of 1.33:1 for CRT TVs. There is less image cropping but still noticeable with aspect ratios such as 2.35:1