These instructions are written for OneNote 2016, but the steps should be similar to versions as far back as OneNote 2010.
Inside a notebook in Microsoft OneNote exist multiple ways to organize content. If you think of the top layer as a filing room, then your notebook is the file room. Your file room may have several cabinets inside, and each file cabinet can have drawers that contain expandable folders that in turn have manila folders. When you finally pull a folder out and open it, you are revealing all the notes, receipts, tax information, instructional guides, and whatever else you keep in paper copy. (I know, I'm assuming you keep your filing rooms nice and neat and organized!)
Section Groups are filing cabinets, and the drawers in each cabinet are Sections. You can start with Sections, but then when you start to need more organization, you can start grouping sections into Section Groups. It's as easy as dragging and dropping to move a section into a new Section Group.
Create a Section in the Section Tabs
Create a Section in the Notebook Navigation Bar
Create a Section Group
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