OneNote is a digital notebook.   With OneNote, you can type notes or record audio at your laptop, sketch or write ideas on your tablet, add a picture from your phone, clip a page from the web, forward an email to your OneNote notebook, find notes instantly, freely move notes around the page, organize those pages into sections, keep your sections in one or more notebooks, switch devices and pick up right where you left off, share your notebooks with others so you can all view and contribute at the same time.  Good video overview (1:23)