signature

A signature is a mark used to indicate identity, intent, or consent. It can be physical, created by handwriting on paper, or digital, created and verified through electronic means. Signatures serve to identify the signer and to signify agreement with the terms of a document, and they are often used to authorize transactions, endorsements, and formal declarations.

Physical signatures are typically the signer's name written in a distinctive style, sometimes with flourishes. Their authenticity is generally assessed by comparing the handwriting to known exemplars and by considering the context, timing, and any corroborating evidence such as witnesses. Because handwriting can vary and can be forged, signatures are sometimes supported by additional measures like notarization or witness attestations.

Electronic signatures encompass electronic symbols, processes, or signatures attached to or logically associated with a record with the intent to sign. Digital signatures are a subset that employ cryptographic methods, such as public-key infrastructure and digital certificates, to verify both the signer's identity and the integrity of the signed data. Digital signatures provide non-repudiation, meaning the signer cannot credibly deny the signature if the verification succeeds.

Legal status and standards: Many jurisdictions recognize electronic or digital signatures as legally binding if the signing process meets statutory requirements, including intent to sign, consent to electronic records, and proper linkage to the document. Examples include the United States ESIGN Act and the European Union's eIDAS regulation.

Verification and security: Verification relies on comparing signatures or validating digital certificates and cryptographic hashes. Security practices include protecting signature samples, using reputable signing platforms, and employing authentication measures for high-value transactions.

History and usage: Signatures have evolved from personal marks and seals in ancient commerce to modern electronic methods, reflecting evolving standards of identity, consent, and record-keeping.