Just a few days ago we shared a number of iPad apps and web tools that allow you to annotate PDFs and web pages. However, with this new Google Drive update, annotating documents has become way easier and simpler. You are now able to directly add your comments on various types of documents right within the Google Drive preview mode without having to open them in Docs, Sheets, or Slides. Document files supported include Office files, PDFs, and images.
Before this update, to comment on a document shared with you you had to open it either in Docs, Slides or Sheets or use a third party app. Now, using Drive preview pane, you will be able to ‘comment, assign tasks, or mention coworkers and the people you work can reply back, even if they’re not using G Suite. Let’s say your coworker opens a file on her Windows laptop using MS Word, she will see your comment in the file and can reply right from there.’