A signature is a mark used by an artist to claim creative responsibility for a work. Artists first began to include their names on their works in the Archaic period in Greece. Greek artists’ names eventually appeared on painted pottery vessels, engraved gems, sculpture bases, and mosaics. However, the vast majority of ancient Greek artworks were not signed. The practice of signing a completed work became more common in the Renaissance, and it has remained common until the present day.

A signature can be a crucial element in attributing and authenticating an artwork. Signatures can be full names, initials, monograms, or symbols. Inspired by Japanese woodblock prints, American painter James McNeill Whistler (1834–1903) signed his paintings with a butterfly symbol. The “AD” monogram of German artist Albrecht Dürer (1471–1528) became so valuable that it was routinely forged by artists copying his work. (Dürer even took one of these forgers to court—the first known copyright action in the history of art). Artists have the freedom to put their signature anywhere on the work, and they sometimes get creative. Signatures can be hidden in plain sight, incorporated into a painting as if engraved on stone or written on a scrap of paper (see cartellino). Web resources here and here.