Electronic signature

An electronic signature is, in the broadest legal sense, any data attached to a document that indicates the signer's intent to agree, from a typed name or a drawn squiggle up to a cryptographically backed seal. The EU's eIDAS regulation sorts these into tiers, and the distinction matters when a signature has to stand up later.

A simple electronic signature (SES) is the basic level: a pasted image of a handwritten signature, a checkbox, an email confirmation. An advanced signature (AES, not to be confused with the cipher) is uniquely linked to the signer and detects later tampering. A qualified electronic signature (QES) is the strongest tier, created with a certified device and a qualified certificate, and in the EU it carries the same legal weight as a handwritten signature. Higher tiers need a trusted identity provider; the simpler ones do not.

For everyday agreements, a visible signature placed and flattened onto the page is often all that is required. Adding that mark on your own device means the document, and whatever it commits you to, is never exposed to a signing platform before you choose to send it.