A digital signature is a mathematical scheme for demonstrating the authenticity of a digital message or document, which can be used with any kind of message, whether it is encrypted or not, simply so that the receiver can be sure of the sender's identity and that the message arrived intact.
A digital signature is an electronic signature, which can be used to authenticate the identity of the sender of a message and possibly to ensure that the original content of the message or document that has been sent is unchanged. Digital signatures cannot be imitated by someone else, and can be automatically time-stamped and are also easily transable. The ability to ensure that the original signed message arrived means that the sender cannot easily renounce it later.
Sometimes, Digital signatures are used to implement electronic signatures, a broader term that refers to any electronic data that carries the intent of a signature, but not all electronic signatures use digital signatures. However, laws concerning electronic signatures do not always make clear whether they are digital cryptographic signatures in the sense used here, and so their importance, somewhat confused.
Digital signatures employ a kind of asymmetric cryptography. Message is sent by an insecure channel that gives the receiver reason to believe the message was sent by the claimed sender. Digital signatures are equivalent to traditional handwritten signatures in several respects, properly implemented digital signatures are more difficult to forge than the handwritten type.