The Sticky Note tool in Adobe Acrobat and Adobe Reader allows for commenting on your business PDF files. The tool can display notes in multiple colors and styles, just like its paper-based cousin ...

The Sticky Note and Highlight tools are only available in Adobe Reader if the document author enabled Reader comments when she created the PDF.

You can get sticky notes on your Mac through the Stickies application, and use it to write and edit notes to create reminders on your desktop.