This is an example of Nested Accordion with verticle steps inside each accordion. Here the panel is created inside the panel to create a nested view. To create this nested view we have a super accordion defined as panel-group and then the panels containing the header and body for each accordion. Now each of these panel-body defines a new panel which would create a new group of the accordion. The data-toggle is set to collapse to give a collapsible behavior to each accordion. The innermost body contains some listed information; You would rarely see, but this could be useful in website for educational to display large content or on the sites which deals with different variety yet categories under one particular menu. You can use this on your website.