**The important part to understand is, that to make the section tree fully navigational, at least the lower-most section needs a content file. (e.g. `_index.md`).**
With the available [section variables and methods](#section-page-variables-and-methods) you can build powerful navigation. One common example would be a partial to show Breadcrumb navigation:
Hugo will automatically create pages for each section root that list all of the content in that section. See the documentation on [section templates][] for details on customizing the way these pages are rendered.
By default, everything created within a section will use the [content type][] that matches the root section name. For example, Hugo will assume that `posts/post-1.md` has a `posts` content type. If you are using an [archetype][] for your posts section, Hugo will generate front matter according to what it finds in `archetypes/posts.md`.