The main goal of digital signature is the same as handwritten signature, to evidence the identityt of the one who represents the signature action.

Digital signature based on the use of digital certificates, is the technology which best evidence offers.

Beacuse of this, every time more countries have addapted legislation which describes the use of this technology, and makes the legal value equal to handwritten signature. In example, there's a common frame for UE, and regulation for many countries in Southamerica.