authentication

1. General: Verification of the genuineness of a document or signature, to make it effective or valid. It usually takes the form of a sealed or stamped certificate that confirms the authority of a public official (such as judge or a notary public) or of a signatory.

2. Computer access: Verification of the identity of a user through a code such as a password.

3. Electronic-commerce: Measure employed to ensure that the entity requesting access to an online system is what or who it claims to be, and to counter (by using passwords, authentication certificate, or other identification devices or procedures) any inappropriate or unauthorized access.