To password protect a PDF in Adobe Acrobat Reader, you'll need the paid Pro version, which starts at $14.99 a month.

Sending important documents? Learn how to password protect PDFs for extra security using easy steps with Adobe Acrobat and free online tools.

How to encrypt and password-protect ZIP files the right way This tip was originally published on IDG Answers, a reader-powered help desk for answering tech questions.

How to Lock PDF Files. In the digital age, business documents can be easily leaked or altered. Adobe's portable document format allows strong encryption using a password, certificate or a rights ...

How to Save Changes to a PDF Form. Adobe Acrobat enables authors to create PDF files, such as product order forms or personal information forms, that Adobe Reader users can fill out.