David Shepherd is one of the most easily identifiable figures in world cricket.
He is a member of the International Cricket Council's elite umpiring panel, having first donned the white coat in 1981.
In the words of England and Wales Cricket Board chief executive Tim Lamb, 'Shep' "remains one of the finest umpires both in domestic and international cricket".
This is his definitive guide to umpiring.
All the calls and signals are displayed with explanatory text outlining why and when umpires would indicate their decisions.
Simply click on the signals displayed on the right-hand side to see what they all mean.