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Signing PDFs: electronic signatures vs digital signatures

Published September 28, 2026 by the ModifyPDF team

“Please sign and return” used to mean printing, signing with a pen and scanning. Today most documents are signed on screen. But the word signature covers two quite different things in the PDF world, and it helps to know which one you are being asked for.

Electronic signatures

An electronic signature is any electronic mark a person uses to show they agree to a document: a typed name, a drawn signature, an image of a handwritten signature, or clicking “I agree”. When you add your signature to a PDF with ModifyPDF’s Sign PDF tool, you are creating a visual electronic signature placed on the page.

In many countries electronic signatures are legally recognized for most everyday agreements. In the United States the ESIGN Act and the Uniform Electronic Transactions Act give them the same standing as handwritten signatures for most transactions, and the EU’s eIDAS regulation recognizes “simple” electronic signatures too. There are exceptions, which often include wills, some property transfers and certain court documents, and the rules differ between countries. If a document has legal weight and you are unsure, check with the person who sent it or with a lawyer.

Digital signatures

A digital signature is a specific technical kind of electronic signature. It uses a certificate and cryptography to bind the signer’s identity to the exact contents of the file. If anyone changes the document after it is signed, PDF readers show the signature as invalid. Digital signatures are typically issued through a signing service or a certificate authority and are common in government forms, regulated industries and high-value contracts. Under eIDAS, “advanced” and “qualified” signatures are built this way.

ModifyPDF does not create certificate-based digital signatures. Adding a visual signature to a digitally signed PDF will usually invalidate the existing digital signature, because the file has changed.

Which one do you need?

  • Everyday forms, letters, quotes, leases, permission slips, HR paperwork: a visual electronic signature is what most people use and what most senders expect.
  • The sender uses a signing platform (they emailed you a link rather than a file): sign inside that platform, which records an audit trail.
  • The document says it requires a digital or qualified signature: use the method the sender specifies.

How to sign a PDF with ModifyPDF

  1. Open Sign PDF and choose your document. It is processed in your browser and never uploaded.
  2. Create your signature: type your name and pick a handwriting style, draw it with a mouse or finger, or upload an image of your signature.
  3. Click where the signature should go, then drag and resize it to fit the signature line.
  4. Add your initials, printed name or the date on the pages that need them.
  5. Download the signed PDF and send it back.

Good habits when signing

  • Read the whole document first, especially anything in small print near the signature line.
  • Initial every page if the document asks for it. It makes swapping pages harder. Adding page numbers in the “Page 1 of 10” format before a multi-party signing helps everyone confirm nothing is missing.
  • Keep a copy of exactly what you signed.
  • Be careful with your signature image. Don’t leave a high-resolution scan of it in shared folders.