Contributor(s): brangas.
  A new batsman to the crease makes (with the help of
  the umpire) a mark on the crease called his guard.
  His guard helps the batsman's judgement of which 
  balls to play at and which to leave alone.

      middle-stump 
      \     leg-stump(of right-hander) 
       \   \ 
  |      \   \      | 
  |       \   \     | 
  |----o---o---o----| 
  |                 | 
 ----------|-|-|------ 
           3 2 1 
            \ 
             \ 
              \ 
              guard chosen (see table below) 


   guard chosen   covering       benefits (anyone?) 
   1 leg        - leg stump    -   ?? 
   2 legs       - b/w the 2    -   ?? 
   3 legs       - middle stump -   ?? 

  Also known as: 
  1 leg   = leg 
  2 legs  = middle and leg 
  3 legs  = middle something or other but What??