What's the easiest way to sign a PDF digitally?

The easiest way depends on whether you need a simple signature or a legally binding digital signature.

Easiest option: use your PDF app’s built-in sign tool

If you just need to add a signature quickly:

• Adobe Acrobat Reader:
  Open the PDF → Fill & Sign → Sign → choose Add Signature → type, draw, or upload your signature.
• Mac Preview:
  Open PDF → click the Markup toolbar → Signature → create or select one → place it.
• Browser / online tools:
  Many let you upload a PDF and add a signature, but avoid sensitive documents unless you trust the service.

If you need a true digital signature

For stronger verification and tamper evidence, use:

• Adobe Acrobat Pro
• DocuSign / Dropbox Sign / SignNow
• A certificate-based digital signature from your organization or certificate provider

This usually involves:

1. Opening the PDF in the signing app
2. Choosing Digital Signature or Certify
3. Selecting your certificate
4. Signing the document

Best quick recommendation

• On Mac: use Preview
• On Windows: use Adobe Acrobat Reader
• For legal workflow: use DocuSign or Adobe Acrobat

If you want, I can give you the exact steps for Windows, Mac, iPhone, or Android.