You can comment in Google Docs using a computer or the Google Docs mobile app on your phone or tablet.

Need to leave a comment in a Microsoft Word document? We'll guide you every step of the way.

It's easy to see the appeal: When you're working at your computer, you can view an incoming text or quickly compose a new one without having to pull your phone out or take it off your charger.

You can easily post on Reddit using the mobile app for Android or iPhone or the desktop website on your computer.