A signature is a usually stylized version of someone's name written on documents as a proof of identity, like a seal, but handwritten.

Signatures may be witnessed and recorded in the presence of a Notary Public.

The traditional function of a signature is evidential: it is to give evidence of (a) the provenance of the document; and (b) the intention 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.

A signature can be referred to in many ways, including the term "John Hancock", after the first of the signers of the Declaration of Independence. A signature of a famous person is sometimes known as an autograph, and is typically written on its own or with a brief note to the recipient, rather than providing authentication for a document.

Special signature machines exist that 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.

Japanese culture does not have signatures, per se, but uses name seals called inkans with the name written in tensho or seal script.

Text automatically appended to E-mail and Newsgroup messages, usually including a name, contact info, and sometimes quotes and ASCII art, is also called a signature (see signature block); however, these are separate from electronic signatures or digital signatures.

The sheet of paper that travels through a printing press which is later cut into separate pages is also referred to as a signature.

See also

• Authentication
• Digital signature
• Signature block