[DonRotolo]

Think of it as a very small wire, and sparks are made to jump from the tip of thr wire to whatever metal workpiece you want to shape. The sparks vaporize a tiny amount of the metal workpiece, and if you do it often enough you spark a hole into the workpiece. Now, control the spark and wire tip position very precisely, and you can shape some really complex shapes. Unlike a waterjet, you don't have to cut all the way through.

EDM - Electical Discharge Machining.

Don