The tag "signature" refers to images that contain an artist's unique signature used to identify an artist. The tag doesn't have much of a purpose but may help in discovering the artist of a picture, such as the unknown_artist tag.

This is not the same thing as artist_name, where the signature is basic enough to resemble printed text.

See also

• autograph – For character signatures.
• credits - When the work has multiple people involved in its creation.
• watermark - A printed version of a signature.