Digital Signature

A digital signature is a mathematical way of proving that a specific person or system approved a particular digital message or document, and that it has not been changed since. It uses a private secret to sign and a matching public value that lets anyone check the signature is genuine.

It is like a tamper-evident wax seal on a letter: it shows who sealed it and reveals if anyone has opened it on the way. Digital signatures matter because they let a business trust an electronic contract, payment instruction or update without meeting in person, which is the foundation of doing serious business online.