Learn about PDFs
Plain-English guides to how PDFs work, how to edit them, and how to keep them private — 25 articles and counting.
PDF basics
What is a PDF?
A clear, jargon-free explanation of what a PDF is, why it looks the same everywhere, and where the format came from.
Read guide →How PDF files actually work
A friendly tour of the internals of a PDF: objects, the cross-reference table, content streams, and why editing one is different from editing a Word doc.
Read guide →How fonts work in PDFs
Why some PDFs display with the wrong font, what font embedding and subsetting mean, and how to avoid text problems.
Read guide →Understanding PDF metadata
What metadata a PDF stores — title, author, software, timestamps — why it can leak information, and how to view or edit it.
Read guide →PDF/A and long-term archiving
What PDF/A is, how it differs from a normal PDF, and when you need it for records that must stay readable for decades.
Read guide →Accessible PDFs explained
How tagged PDFs make documents usable with screen readers, what makes a PDF accessible, and why it matters legally and practically.
Read guide →Editing & pages
How to edit a PDF
The real ways to edit a PDF — add or change text, insert images, annotate, and rearrange pages — and which method fits which job.
Read guide →How to merge PDF files
A simple guide to combining multiple PDFs into a single file, keeping the right page order and quality.
Read guide →How to split a PDF
Extract a page range, pull out a single page, or break a PDF into one file per page — with tips on doing it losslessly.
Read guide →Rearranging PDF pages
Fix sideways scans, drop blank pages, and put pages in the right order — the essential page-management moves.
Read guide →How to add text to a PDF
Type anywhere on a PDF, style it, and add highlights, notes, and shapes — the most reliable way to edit any PDF.
Read guide →What flattening a PDF means
Flattening merges annotations, form fields, and layers into the page. Learn what it does and when it is essential.
Read guide →Watermarks, page numbers & Bates numbering
How to stamp a PDF with a watermark, add page numbers, or apply legal Bates numbering — and when each is used.
Read guide →Security & privacy
How to password-protect a PDF
The two kinds of PDF passwords, how to add one, and how to choose a password that actually protects your document.
Read guide →PDF encryption explained
How PDF encryption works, what AES-256 and key derivation mean, and the limits of what a password can protect.
Read guide →How to redact a PDF safely
The right way to permanently remove sensitive text from a PDF — and the common mistake that leaves it exposed.
Read guide →Client-side vs cloud PDF editors
The privacy difference between PDF tools that upload your files and ones that work entirely in your browser.
Read guide →Removing hidden metadata
Why PDFs carry hidden information about you and your software, and how to clean it before sharing.
Read guide →Signatures
How to sign a PDF
Add your signature to a PDF by drawing it, typing it in a cursive font, or uploading an image — no printing required.
Read guide →Digital signatures vs e-signatures
The important distinction between a drawn e-signature and a cryptographic digital signature that proves who signed and that nothing changed.
Read guide →Converting & OCR
Converting PDF to Word
How PDF-to-Word conversion works, why formatting sometimes breaks, and how to get the cleanest result.
Read guide →How to compress a PDF
What actually makes a PDF large, and the practical ways to shrink one while keeping it readable.
Read guide →What is OCR?
How optical character recognition turns scanned pages and images into real, searchable text — and what affects accuracy.
Read guide →Guides & comparisons
Choosing a free PDF editor
What to look for in a free PDF editor, the trade-offs between browser, desktop, and cloud tools, and the red flags to avoid.
Read guide →PDF vs Word: when to use each
The practical differences between PDF and Word documents, and a simple rule for choosing the right one.
Read guide →Ready to try it?
Every technique in these guides works, for free, in the FreshPDF app — right in your browser.
Open the app