According to the U.S. E-SIGN Act an electronic signature is an electronic sound, symbol, or electronic process that is attached to or logically associated with a contract or another record and executed or adopted by a person with the intent to sign the record.

Purpose

Some documents can be validated through the use of electronic means. An electronic signature validates the document with a unique impression and at some time in the future a hard copy may be sent to a party in order to complete the verification of the document.

Meaning

An electronic impression is used to represent a signature with electronic documents. Most handwritten signatures use ink as the medium of validation. The electronic signature uses the electronic impression as the means to validate an electronic document.

Security

Valid electronic signatures cannot be simply duplicated and they offer more security than handwritten signatures as long as the electronic data is compliant with the law.

Authentication

A valid symbol must be compliant with the law by providing authentication of the party who created it. Once signed the symbol cannot be altered, the party who creates the symbol has to know that they're doing so for the purpose of signing, and the signer must be able to save an original record of the symbol and data that is being signed.

Forbidden Documents

According to the E-SIGN Act, not all types of documentation can be validated by using electronic signatures. Wills, divorce documents, adoption papers and court orders are some of the documents that cannot be validated by electronic signatures.

Source:

Algorithimic Research: What are Electronic Signatures and Digital Signatures?

All About Electronic Signatures: Electronic signatures and e-Contracting digital signature software

E-SIGN Act