Digital signatures are the public-key primitives of message authentication. In the physical world, it is common to use handwritten signatures on handwritten or type messages. They are used to bind signatory to the message.
Similarly, a digital signature is a technique that vines a person/entity to the digital data. This binding can be independently verified by the receiver as well as any third party.
Digital signature is a cryptographic value that is calculated from the data and a secret key known only by the signer.
Importance of digital signature: