Menus are a collection of links, also known as menu items, that are used to navigate a website. Standard Drupal menus are primarily displayed as a list of links that, when clicked on, will expand downward if there are sub-items.
Drupal starts with a few standard menus that can be used immediately. These menus are: Navigation, Primary Links, and Secondary Links. Custom menus can also be created. For example, an Employee menu could be created that contains all the links an employee would need to perform a job.
One of the great features of Drupal Menus is the ease of use. Content can be quickly added to a menu directly from the content submission form, as described in the Common Node Type Elements section of this book. For more fine-tuned menu control, though, Drupal provides an interface at Admin menu > Site building > Menus where users can reorder menu items using drag-n-drop. This control panel is also where custom menus can be created.
Menus work in conjunction with Drupal's flexible Blocks feature. If a new menu is added to the system, a block with the same name will automatically be created which can be enabled and placed in a region of your choice by going to Admin menu > Site building > Blocks.