Signature

A signature is a handwritten (and sometimes stylized) depiction of someone's name (or some other identifying mark) that a person writes on documents as a proof of identity and will. It acts as a seal.

The traditional function of a signature is evidential: it is to give evidence of (a) the provenance of the document (identity); and (b) the intention (will) of an individual with regard to that document. For example, the role of a signature in many consumer contracts is not to provide evidence of the identity of the contracting party, but rather to provide evidence of deliberation and informed consent. Signatures may be witnessed and recorded in the presence of a Notary Public to carry additional legal force. On legal documents, an illiterate signatory can make a "mark" (often an "X" but occasionally a personalized symbol), so long as the document is countersigned by a literate witness.

There are many other terms which are synonymous with 'signature'. One is John Hancock, named after the first of the signers of the United States Declaration of Independence. The signature of a famous person is sometimes known as an autograph, and is then typically written on its own or with a brief note to the recipient. Rather than providing authentication for a document, the autograph is given as a souvenir which acknowledges the recipient's access to the autographer.

Special signature machines, called autopens are capable of automatically reproducing an individual's signature. These are typically used by people required to sign many documents, for example celebrities, heads of state or CEOs.

Several cultures whose languages use writing systems other than alphabets do not share the Western notion of signatures per se: the "signing" of one's name results in a written product no different from the result of "writing" one's name in the standard way. For these languages, to write or to sign involves the same written characters. Three such examples are Chinese, Japanese, and Korean. In Japanese culture, people typically use name-seals or inkan with the name written in tensho script (seal script) in lieu of a handwritten signature (also see Calligraphy).

In e-mail and newsgroup usage, another type of signature exists which is independent of one's language. Users can set one or more lines of custom text known as a signature block to be automatically appended to their messages. This text usually includes a name, contact information, and sometimes quotations and ASCII art. Some web sites also allow graphics to be used. Note, however, that this type of signature is not related to electronic signatures or digital signatures, which are more technical in nature and not directly readable by human eyes.

By analogy, the word "signature" may be used to refer to the characteristic expression of a process or thing. For example, the climate phenomenon known as ENSO or El Nino has characteristic modes in different ocean basins which are often referred to as the "signature" of ENSO.

• Images of signatures
• manu propria (m.p.)