What PDF Annotation Is For
Annotation means adding marks to a document without changing the original text. You're adding a layer on top — highlights, comments, arrows, drawings — that communicate your thoughts about the content.
This is different from editing. When you annotate, the original words stay exactly as they are. When you edit, you change them. Annotation is for reviewing, studying, giving feedback, and marking up documents for discussion.
Annotation Tools Available
Our [Annotate PDF](/annotate-pdf) tool gives you:
Highlight — Select any text and apply a colour. Yellow for key points, green for supporting evidence, red for concerns, blue for action items. Build a personal colour system.
Sticky note — Click anywhere on the page to place a comment bubble. Write as much as you need. The note collapses to a small icon and expands on click — doesn't obscure the document.
Text box — Add typed text directly on the page. Good for adding missing information, writing inline corrections, or labelling sections.
Freehand drawing — Draw with mouse or stylus. Circle things, draw arrows between related sections, sketch diagrams.
Arrow — Click-drag to place a precise directional arrow pointing at something specific.
Shapes — Rectangles and circles for boxing or circling important areas.
Strikethrough — Mark text for deletion in editing workflows.
Underline — Emphasise text differently from highlighting.
How to Annotate a PDF
Open our [Annotate PDF](/annotate-pdf) tool
Upload your PDF
Select your annotation tool from the toolbar
Apply it to the page
Switch tools and continue annotating
Click Download when done — all annotations are embedded in the PDF
The annotations are saved permanently in the file. Anyone who opens the PDF — in Adobe Reader, Chrome, Preview, or any standard viewer — will see your marks.
Annotation for Different Purposes
Reviewing a Document
When reviewing a contract, report, or proposal:
- Highlight sections that need discussion
- Add sticky notes with specific questions or concerns
- Use red highlight (or strikethrough) for content that needs to change
- Use green highlight for content you approve
- Add arrows pointing to specific clauses with comments explaining your concern
When you return the annotated PDF, the other party can see exactly what you're responding to — much clearer than numbered comments in a separate email.
Studying and Research
Academic annotation workflow:
- Yellow highlight: main arguments and key claims
- Green highlight: evidence and supporting data
- Blue highlight: definitions and terminology
- Sticky notes: your own summary of each section in a few words
- Red highlight: things that seem questionable or need verification
After annotating a paper this way, you have a personalised study guide built into the document itself.
Giving Design or Document Feedback
When reviewing creative work, proposals, or visual documents:
- Use arrows to point at specific visual elements
- Text boxes to describe what should change ("reduce font size here")
- Circles to highlight specific problem areas
- Sticky notes for longer explanations
This is clearer than describing locations ("third paragraph, second column, the image on the left") in a separate document.
Keeping Annotations vs Making Changes Permanent
Annotations are a separate layer from the document. They can be removed or modified by someone with PDF editing software. If you want to lock annotations so they can't be altered:
Annotate your PDF
Run it through our [Flatten PDF](/flatten-pdf) tool
Flattening merges the annotation layer into the page permanently — marks become part of the document and can't be removed
Do this before submitting documents with your annotations, or before archiving a reviewed version.
Annotate vs Edit — Choosing the Right Approach
| Goal | Use |
|---|---|
| Add comments without changing content | Annotate PDF |
| Change existing text | [Edit PDF](/edit-pdf) or [PDF to Word](/pdf-to-word) |
| Remove content permanently | [Redact PDF](/redact-pdf) |
| Mark documents as reviewed | Annotate + Flatten |
Frequently Asked Questions
Will the recipient see my annotations if I email the PDF?
Yes, as long as you download the annotated PDF and send that file. Annotations are embedded in the PDF — anyone opening it will see them in any standard PDF viewer.
Can I remove annotations I've added?
Before downloading, you can undo or delete any annotation. After downloading, re-upload the annotated PDF and remove specific marks using the selection tool.
Can I annotate a scanned PDF?
Yes — you can place highlights, sticky notes, and drawings on top of scanned pages. However, text highlighting works by selecting text, which requires actual text data. For scanned PDFs, use the drawing/shape tools to mark areas. If you want true text highlighting on scanned content, run [OCR](/ocr-pdf) first to add a text layer.
Is there a limit on how many annotations I can add?
No. Add as many annotations as needed across any number of pages.