The following are three SharePoint levels that are part of the design ecosystem:
First Level: This represents the top-level navigation, typically displayed as tabs across the top of a site.
Second Level: Below the top-level tabs, one has the second level. These are the sub-links associated with each tab. They provide more specific navigation within a category.
Third Level: The third level is indented or below the second level. It’s essentially the sub-sub-links associated with the second-level sub-links.
