Any site needs some sort of navigation, right? Drupal not only maintains content, but also provides details about how the site itself is organized, that is, it structures how content is related.
The principle way that it does this is through the menu subsystem. The latter provides APIs to generate, retrieve, and modify elements that describe the site structure. Put in common parlance, it handles the system's navigational menus.
Menus are hierarchical, that is, they have a tree-like structure. A menu item can have multiple children, each of which may have their own children, and so on. In this way, we can use the menu system to structure our site into sections and subsections.
In this book, we will see how we can work programmatically ...