Pages on your Drupal site are laid out in regions, which can include the header, footer, sidebars, and main content section; your theme may define additional regions. Blocks are discrete chunks of information that are displayed in the regions of your site’s pages. Blocks can take the form of menus, the output from modules, or dynamic and static chunks of information that you’ve created yourself.
There are three standard menus in Drupal: Primary Links, Secondary Links, and Navigation. Primary and Secondary links are built by site administrators, and displayed automatically in the page header of many themes. Navigation is the catch-all menu that contains your administration menus, as well as links supplied by modules on your site. You can also create your own custom menus, and display them by enabling their blocks.
You can customise menus in several ways, such as reordering menu items by setting their “weight” or simply dragging into place, renaming menu items, and changing the link title. You can move a menu item into a different menu by editing the Parent property of the menu item.
You can also add custom menu items to a menu, from the Add menu item tab of the Menu administration screen. To create a menu item, you will need to provide the path to the content.   _{Your Comment}