What is "artist's proof"

Proof \Proof\, n. [OF. prove, proeve, F. preuve, fr. L. proba, fr. probare to prove. See Prove.]

1. Any effort, process, or operation designed to establish or discover a fact or truth; an act of testing; a test; a trial.

   For whatsoever mother wit or art Could work, he put in proof.
   --Spenser.

   You shall have many proofs to show your skill.
   --Ford.

   Formerly, a very rude mode of ascertaining the strength of spirits was practiced, called the proof.
   --Ure.

2. That degree of evidence which convinces the mind of any truth or fact, and produces belief; a test by facts or arguments that induce, or tend to induce, certainty of the judgment; conclusive evidence; demonstration.

   I'll have some proof.
   --Shak.

   It is no proof of a man's understanding to be able to confirm whatever he pleases.
   --Emerson.

   Note: Properly speaking, proof is the effect or result of evidence, evidence is the medium of proof. Cf. Demonstration, 1.

3. The quality or state of having been proved or tried; firmness or hardness that resists impression, or does not yield to force; impenetrability of physical bodies.

4. Firmness of mind; stability not to be shaken.

5. (Print.) A trial impression, as from type, taken for correction or examination; -- called also proof sheet.

6. (Math.) A process for testing the accuracy of an operation performed. Cf. Prove, v. t., 5.

7. Armor of excellent or tried quality, and deemed impenetrable; properly, armor of proof. [Obs.]
   --Shak.

   Artist's proof, a very early proof impression of an engraving, or the like; -- often distinguished by the artist's signature.

   Proof reader, one who reads, and marks correction in, proofs. See def. 5, above.

   Syn: Testimony; evidence; reason; argument; trial; demonstration. See Testimony.

n. A very early proof impression of an engraving, or the like; -- often distinguished by the artist's signature.

An artist's proof is, at least in theory, an impression of a print taken in the printmaking process to see the current printing state of a plate while the plate (or stone, or woodblock) is being worked on by the artist. A proof may show a clearly incomplete image, often called a working proof or trial impression, but in modern practice is usually used to describe an impression of the finished work that is identical to the numbered copies. There can also be printer's proofs which are taken for the printer to see how the image is printing, or are final impressions the printer is allowed to keep; but normally the term "artist's proof" would cover both cases.

Artist's proofs are not included in the count of a limited edition, and sometimes the number of artist's proofs, which belong to the artist, can be twenty or more. By convention, the artist is not supposed to sell these at once.