Editing Authentication (section)

==In art, antiques and anthropology==
{{Main|Provenance}}
Authentication can be considered to be of three types:

The ''first'' type of authentication is accepting proof of identity given by a credible person who has first-hand evidence that the identity is genuine. When authentication is required of art or physical objects, this proof could be a friend, family member, or colleague attesting to the item's provenance, perhaps by having witnessed the item in its creator's possession. With autographed sports [[memorabilia]], this could involve someone attesting that they witnessed the object being signed. A vendor selling branded items implies authenticity, while they may not have evidence that every step in the supply chain was authenticated. 

The ''second'' type of authentication is comparing the attributes of the object itself to what is known about objects of that origin. For example, an art expert might look for similarities in the style of painting, check the location and form of a signature, or compare the object to an old photograph. An [[archaeologist]], on the other hand, might use carbon dating to verify the age of an artifact, do a chemical and [[spectroscopy|spectroscopic]] analysis of the materials used, or compare the style of construction or decoration to other artifacts of similar origin. The physics of sound and light, and comparison with a known physical environment, can be used to examine the authenticity of audio recordings, photographs, or videos. Documents can be verified as being created on ink or paper readily available at the time of the item's implied creation.

Attribute comparison may be vulnerable to [[forgery]]. In general, it relies on the facts that creating a forgery indistinguishable from a genuine artifact requires expert knowledge, that mistakes are easily made, and that the amount of effort required to do so is considerably greater than the amount of profit that can be gained from the forgery.

In art and antiques, certificates are of great importance for authenticating an object of interest and value. Certificates can, however, also be forged, and the authentication of these poses a problem. For instance, the son of [[Han van Meegeren]], the well-known art-forger, forged the work of his father and provided a certificate for its provenance as well.

Criminal and civil penalties for [[fraud]], [[forgery]], and counterfeiting can reduce the incentive for falsification, depending on the risk of getting caught.

Currency and other financial instruments commonly use this second type of authentication method. Bills, coins, and [[cheque]]s incorporate hard-to-duplicate physical features, such as fine printing or engraving, distinctive feel, watermarks, and holographic imagery, which are easy for trained receivers to verify.

The ''third'' type of authentication relies on documentation or other external affirmations. In criminal courts, the [[rules of evidence]] often require establishing the [[chain of custody]] of evidence presented. This can be accomplished through a written evidence log, or by testimony from the police detectives and forensics staff that handled it. Some antiques are accompanied by certificates attesting to their authenticity. Signed sports memorabilia is usually accompanied by a certificate of authenticity. These external records have their own problems of forgery and [[perjury]] and are also vulnerable to being separated from the artifact and lost.