A printmaking process in which an etching needle is used to draw into a wax ground applied over a metal plate. The plate is then submerged in a bath of acid, which “bites” into the metal surface only where it is unprotected by the ground. The ground is then removed, ink is forced into the etched depressions, the un-etched surface is wiped clean, and an impression is printed on paper. Web resource here.
Rembrandt van Rijn. Self-Portrait. Etching. 1630.