In the comparative study of shorthand systems, shading refers to the use of light or thin lines in contrast to dark or thick lines.
Example: in Pitman shorthand a light vertical line represents the sound of T and a heavy line of the same size and direction stands for D. Two consonants are often written back-to-back, sometimes requiring the writer to change from heavy shading to a light line in the middle of the combination. In Pitman even tiny dots and dashes must be drawn correctly as either heavy or light!
For people who have a knack for penmanship, shading is relatively easy to accomplish with fountain pens. It is harder to achieve with pencils, ball-point pens and fingers on touch-screens.
Enthusiastic users of systems that require shading say it doesn’t matter – you can write with a non-shading utensil and you will still be able to figure out whether you meant to write bee or pee, cash or gash.
Shorthand systems that do not use shading are sometimes called light-line systems.