“Signing a PDF” can describe very different operations. In everyday use it often means placing the visual appearance of a handwritten signature on a page. In other contexts, an electronic or digital signature refers to a process designed to identify a signer and protect document integrity.
GuideBest practicesBeginner
Add a signature to a PDF: what you need to know
Understand how to place the visual appearance of a handwritten signature in a PDF and why this is not the same as a cryptographic electronic signature.
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Adding a visual handwritten signature
Add a signature to a PDF lets you place a visual representation of your signature on a chosen page, adjust its size and position, and generate a new PDF. This is appropriate when the requirement is explicitly to complete the document visually.
What this does not do
An image of a signature is not, by itself, a cryptographic or qualified electronic signature. It does not automatically create a digital certificate, prove the identity of the person who placed it, or provide a mechanism that detects every later modification.
Legal, contractual or administrative contexts may impose specific requirements. If the recipient asks for a certified or qualified electronic signature, a dedicated service or device may be necessary.
Visual, electronic and digital signatures are not interchangeable
A visual signature is simply what appears on the page. “Electronic signature” is a broader concept for expressing agreement electronically. Some digital-signature systems additionally use certificates and cryptography to verify integrity and an identity associated with the certificate.
These levels provide different guarantees. A visible autograph on a PDF does not by itself tell you what legal or technical evidence exists behind the file.
Integrity is a separate property
A cryptographic signature can make later file modifications detectable. A signature image placed on a page does not provide that property by itself; it becomes a visual element of the generated PDF.
That does not make visual signatures useless. They are practical when the recipient expects a visibly completed document. The important point is not to attribute guarantees they do not provide.
Prepare a clean signature image
Avoid shadows, grey paper backgrounds and large empty margins. Use a source that remains sharp at the displayed size. If you need a logo, stamp or illustration rather than a signature, use Add an image to a PDF instead.
Privacy matters
A signature is personal information, and the document around it may be sensitive as well. Keep unnecessary copies to a minimum and review the destination before sharing. The guide PDF and privacy: edit a document without sending it to a server explains the Local First approach in more detail.
Key point
Adding a signature image is a visual document-editing operation. It must not be confused with a certified, qualified or cryptographically verifiable electronic-signature process.