A Digital Signature\xa0is an electronic form of a signature. Just as one authenticates a document with handwritten signature, a digital signature authenticates electronic documents.
A digital signature is a digital code that can be attached to electronically transmitted message that uniquely identifies the sender

A digital signature is a digital code (generated and authenticated by public key encryption) which is attached to an electronically transmitted document to verify its contents and the sender\’s identity.
A digital signature is a mathematical scheme for demonstrating the authenticity of digital messages or documents.