How to Annotate a PDF

Published on May 27, 2026 by Lily Cichanowicz, M.A.

Annotating a PDF is when you add notes, comments, highlights, or drawings to a PDF document. This is useful for studying or when giving feedback at work.

This guide shows you how to annotate a PDF in three simple steps using Quillbot’s free Annotate PDF tool.

      Key takeaways
  • Annotating a PDF is when you add comments, drawings, notes, images, or highlights to a PDF document.
  • This article walks you through how to use Quillbot’s Annotate PDF tool in three easy steps: Upload, adjust, and download.
  • You’ll also find useful tips for making the most out of the Annotate PDF tool and resolving common issues like removing annotations or adjusting your document’s formatting.

Continue reading: How to Annotate a PDF

How to Flatten a PDF

Published on May 11, 2026 by Lily Cichanowicz, M.A.

Flattening a PDF is when you merge all interactive elements—like signatures, form fields, and annotations—into a single layer. This way, the document appears correctly when you print or share the file with others. It also means that the document will no longer be editable.

This guide shows you how to flatten a PDF with ease using Quillbot’s free Flatten PDF tool.

Key takeaways
  • Flattening a PDF locks signatures, form fields, annotations, and other interactive elements into a single non-editable layer. It preserves formatting and prevents unwanted changes when sharing or printing documents.
  • In this guide, you’ll learn how to quickly flatten a PDF using Quillbot’s free Flatten PDF tool in just three simple steps: upload, flatten, and download.
  • You’ll also discover practical tips for avoiding common issues like large file sizes, distorted text, missing content, and unsearchable PDFs.

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How to Use an AI Summarize PDF Tool

Published on April 29, 2026 by Quillbot.

When you’re faced with a long PDF that may or may not contain the information you’re looking for, AI tools like Quillbot’s free online PDF Summarizer can save you time by providing an overview of its contents. After you summarize a PDF, you can also ask follow-up questions to locate specific information in the document or clarify parts of the summary in more detail.

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How to Password Protect a PDF

Published on March 5, 2026 by Quillbot.

We use PDFs because they’re such a convenient format for sharing documents. But if a file can be opened by anyone in just a few clicks, that same convenience can quickly become a drawback when it comes to limiting access to it.

That’s why it’s a good idea to password-protect PDFs that contain sensitive information—a quick and easy process with a free online tool like Quillbot’s Protect PDF.

Continue reading: How to Password Protect a PDF