Intaglio is a generic term used to indicate prints created where the ink is held in a groove in a metal or plexiglass plate. There are a number of techniques used to create the grooves in the metal plate. Some of those are referred to as hard ground, soft ground. aquatint, and deep etch.
One thing to keep in mind is that the deeper the groove, the more ink it holds making a darker line. A delicate line on an etching print was created by a shallow groove holding very little ink.