map

aspect ratio

normal television

 
4
3 tv picture with 4:3 aspect ratio

 

digital television

  16
9 dtv picture with 16:9 aspect ratio
  extra sections
The "aspect ratio" of a screen is the width of the screen divided by its height. Normal televisions have a ratio of 4:3. Digital tv modifies this ratio to 16:9 to give that "Widescreen" feeling. Effectively you get two extra sections on the sides of your screen.
EPSRC