Aquatint is an intaglio printmaking technique, a variant of etching.

Intaglio printmaking makes marks on the matrix (in the case of aquatint, a copper or zinc plate) that are capable of holding ink. The inked plate is passed through a printing press together with a sheet of paper, resulting in a transfer of the ink to the paper. This can be repeated a number of times, depending on the particular technique.

Like etching, aquatint uses the application of acid to make the marks in the metal plate. Where the engraving technique uses a needle to make lines that print in black (or whatever colour ink is used), aquatint uses powdered rosin which is acid resistant in the ground to create a tonal effect. The tonal variation is controlled by the level of acid exposure over large areas, and thus the image is shaped by large sections at a time. Another tonal technique, mezzotint, begins with a plate surface that is evenly indented so that it will carry a fairly dark tone of ink, then smoothing areas to make them carry less ink and thus print a lighter shade; or, beginning with a smooth plate, areas are roughened to make them darker; or, these two techniques may be combined.