How to annotate a PDF for review without special software

Reviewing a contract, a report, a proposal or a student’s essay usually means marking it up. You want to highlight a sentence, circle a number, add a comment and send it back, without buying software or learning a new program. This guide explains what annotations are, how to use each kind well, how to agree conventions with other reviewers, and how to finish the file so it goes out in the state you intend.

What annotations really are

An annotation is a separate object that sits on top of a PDF page. It isn’t part of the page’s own content. A highlight, a sticky note, a drawn rectangle or a text box is stored in the file as its own item, with a position, a colour and sometimes some text. Because it is separate, a reader can show it, hide it, move it or delete it without touching the document underneath.

That design is what makes review work. It is also why annotations are not a way of changing a document. They comment on it.

Annotate or edit?

The markup tools and when to use each

• Highlight. Marks text you want the author to look at again. Use it for “this is the part I mean”, and keep it to a line or two so the page stays readable.
• Underline. Draws attention more lightly than a highlight. A good choice for a defined term, a date or a number you want checked.
• Strike-through. Suggests a deletion. Pair it with a sticky note if you also have a replacement.
• Sticky note. A comment in a small pop-up. This is where your explanation goes. One note should make one point.
• Rectangle. Frames a table, a chart or a whole paragraph. Use a thin line so it doesn’t crowd the text.
• Pen. Freehand marks: circling, arrows, underlining by hand. Quick on a tablet and awkward on a laptop trackpad.
• Text box. Text written straight on the page, for a short instruction such as “move to section 3”.

Agreeing conventions

A page covered in unexplained marks is hard to act on. Two minutes of agreement before review saves a lot of confusion afterwards. A simple scheme:

If more than one person reviews, give each their own colour instead, and start every note with initials. Whichever you choose, say it in the email that carries the file. Be specific in every note: “Check against the 2025 figures” is useful and “??” is not.

Marking up a document

1. Open the file in Annotate PDF. The page appears large, with a toolbar above it. The file stays on your device the whole time.
2. Pick a tool and a colour. The colour you choose stays until you change it. Choosing a tool resets to a sensible default for it.
3. Mark the page. Drag for highlights, underlines, strike-throughs, rectangles and text boxes. Click for a sticky note. Draw with the pen.
4. Switch to Select to adjust. Click anything to move it, resize it, recolour it or delete it. Undo and Redo cover mistakes.
5. Move through the pages with the arrows or by typing a page number.
6. Save. Press Save annotations. They are written into the file as standard annotations, and you download the new copy.

Open the saved file in a different reader before you send it. If your marks appear there, they will appear for your reviewers.

Writing comments that get acted on

The best markup is the kind the author can act on without phoning you. A few habits make the difference:

• Say what and why. “Shorten this” is a request. “Shorten this: the board will stop reading after two lines” gives the author a reason to agree with you.
• Offer the replacement. If a strike-through removes a sentence, put the new wording in a sticky note beside it, so nobody has to guess what you wanted.
• Mark severity. Tell the author which comments must be fixed and which are suggestions. Prefix a note with “Must” or “Optional” and nobody has to ask.
• Keep marks next to what they mean. A note two paragraphs away from the sentence it concerns will be misread. Highlight the exact words, then place the note beside them.
• Don’t mark everything. If every line is highlighted, none of it stands out. Mark what matters, and put general impressions in the covering email.
• Review once, then send. Read your own comments through before you save. Deleting a snappy remark takes a second; unsending it takes an apology.

Several reviewers

Collecting feedback from several people is where review gets messy. A basic file-based approach has two workable patterns:

• One file, passed along. Each reviewer adds their marks in turn, using their own colour, then hands the file on. It is orderly, but slow, and it makes later reviewers read earlier reviewers’ comments.
• Separate copies, collected by one person. Everyone marks their own copy, and one person reads them side by side and summarises. It is quick, and the collector does the work.

Combining annotations from separate copies into one file is something a simple tool can’t do reliably, and Merge PDF joins documents page by page, not the marks on them. Plan for a person to do the collecting.

Finishing and sending

What you do next depends on who receives the file.

• Back to the author. Send the annotated file as it is. They need to be able to see, reply to and delete the marks.
• To someone who needs the markup but must not change it. Run it through Flatten PDF. The marks become part of the page and can’t be moved or removed. Keep your unflattened copy.
• To someone outside the review. Remove the comments with Remove metadata so candid notes don’t go with the file, or flatten only the marks you want them to see.
• For long-term records. Flatten, then keep the original separately.

Phones, tablets and keyboards

Touch screens work well for markup. Use a finger or stylus to draw and place items. While a drawing tool is active, the page doesn’t scroll under your finger, so switch to Select, then scroll. On a phone, rotate to landscape for a wider page.

You can do all the placing without a pointer too. Choose a tool, press Place in the middle, then use the arrow keys to move the new item and Shift with the arrows to resize it. Press Delete to remove the selected item. Pen strokes need a pointer, since they follow the movement of your hand.