A signature is a special combination of data assigned to a person for identification purposes. A signature is largely equivalent to an electronic business card that can be attached to a document, such as an e-mail or a fax.
In the case of e-mails, this is referred to as a mail signature. The prerequisite for such a signature is an e-mail program that includes this option. Mostly such mail signatures consist only of name and e-mail address. Sometimes the postal address and a link to the author's homepage are added. Signatures are supposed to replace the headers that some e-mail programs automatically cut off when they are received.
Signatures are divided into signature classes depending on the security requirements. There is the electronic signature, the simple electronic signature, the advanced electronic signature and the qualified electronic signature. In addition to the normal signatures, there are the digital signatures, which are created using an algorithm. Digital signatures are intended to guarantee the authenticity of a document and the sender, whereas mail signatures serve a cultural purpose.