After Effects Nomenclature
The pick whip is simple to use. Left-click and hold down the mouse button as you drag the pick whip icon (looks like a spiral) to its target property. Once the target is highlighted, release and the code is inserted in the expression field.
As the pick whip is a dynamic tool, I’ve created a 39 second video to demonstrate both using the pick whip to create code in an expression field, and to parent one layer to another.