Sections appear along the top of the page and look similar in shape to the tabs you find on the yellow manila folders:
Sections belong inside of notebooks. So when you switch to another notebook, you'll see the section tabs associated with that notebook change to display all the sections contained within it. Some people like to name their section tabs by topic, such as what the example picture shows above. In this example, each tab contains notes about a given subject in school.
Some people like to name their section after a customer's name or a client. Then they store notes relating to that customer in the section. They can add new notes about the customer during meetings, or perhaps refer to notes they've previously taken about them.
Some might name their section after the name of a particular task they have at work. Or they might name it after a weekly meeting. Others like to name them after a topic or a particular subject. There are no right or wrong section names, just use names that appeal to you and help you to more easily organize your stuff. Since a section represents a single file at the Windows level, there are certain characters that cannot be used in the section name. These include all of the following characters: \ / : * ? " < > |
Sections can also be stored inside of Section Groups. Section groups give you an extra layer of organization. Like sections, they are contained in notebooks and appear along the top of the page, next to the section tabs.
To create a section group, click File -> New (or right-click the empty area immediately to the right of the section tabs) -> Section Group. You can also use the New button dropdown on the Standard toolbar.