$Signature 
(1) A special authentication code, such as a password, which you give prior to accessing a system or prior to the execution of a task to prove your identity. (2) A sentence or paragraph used to end email messages and comments posted on the Internet. Normally a signature would be consistent and would include a short advert for your company or your email address for replies. Most email programs can add a signature automatically to the end of all email messages you send.