Adobe Reader lets you mark up PDFs easily. After you add a highlight, you can insert comments about it.
Adding a Highlight
![](https://media.screensteps.com/image_assets/assets/000/186/597/original/22e6b6ca-1355-4074-a62e-5ae6c8ad83c6.png)
Reader displays the highlight.
Add a Comment to the Highlight
Now that you've created a highlight, you can add comments about it.
![](https://media.screensteps.com/image_assets/assets/000/186/593/original/bff9d65d-25dc-4162-94ff-a319b0a59560.png)
Reader displays the text of your comment on the right panel.
![](https://media.screensteps.com/image_assets/assets/000/186/595/original/47763c52-e918-4afe-954e-529ba0cac57c.png)
You can use a similar technique to add comments to other mark ups in Adobe Reader.