What is the mezzotint printmaking process?

Keep Ludwig von Siegen in mind since he created one of the most complex printing methods—the mezzotint—in the first half of the seventeenth century.

What is the mezzotint printmaking process?
The Adoration of the Shepherds: A Night Piece by Rembrandt. Ludwig von Siegen's creation of mezzotint engraving may have been inspired by Rembrandt's prints during a 1642 visit to Amsterdam. Photo by form PxHere