PDF guides

Short, practical guides to the PDF jobs that come up at work, school and home. Each one explains what’s really going on and links to the free tool that does the job in your browser.

• How to compress a PDF so it fits in an emailEmail attachment limits, why some PDFs are huge, and how to shrink a PDF enough to send it while keeping text sharp.
• How to redact a PDF properly (and why black boxes often fail)Drawing a black rectangle over text doesn’t remove it. Learn what real redaction is, what to redact, and how to check your file before sharing.
• Signing PDFs: electronic signatures vs digital signaturesThe difference between a typed or drawn electronic signature and a certificate-based digital signature, and which one your document needs.
• PDF passwords explained: open passwords, permissions and encryptionWhat the two kinds of PDF password do, how strong PDF encryption is, and how to choose a password you won’t regret.
• What is PDF/A, and when do you need it?PDF/A is the archival version of PDF required by many courts, governments and archives. Here’s what it is and how to pick the right level.
• How to combine PDFs into one file (and keep them in order)Merge several PDFs into a single document, reorder pages across files and avoid the common problems with mixed page sizes and protected files.