Object
Multiples, and the market they created
Prints are multiples, and the value is in the impression: which state, how early, and how many survive. The image is the same; the object is not.
History
Old master prints (15th–18th century) are judged by state and impression rather than by the image alone.
The nineteenth and twentieth centuries add the poster, the limited edition and the numbered print — multiples made deliberately.
What to look for
Margins intact, plate mark visible, and a state or edition number that can be checked.
In this group
The searches this object is worth looking at. Each opens the collection for it.