Drupal, like many other CMS, allows you to combine links to pages in the menu. You can add new menus and links to them when creating new pages.
After installing the standard version of Drupal 8, we have 5 menus.
Main navigation - this is the previous menu from Drupal 7 main-menu (primary links). By default, there is a link to the home page.
User account menu - This is a menu from Drupal 7 user-menu. Here are links to your personal account and exit from it.
Tools - menu with links to content management.
Footer - menu for the footer of the page, by default there is a link to the contact form.
Administration - a large menu duplicating the top menu of the administrator.
The menu in the Drupal is displayed in the form of a block, blocks can be displayed on the block layout control - Structure - Block layout:
You can add new menus, for this go to the page Manage - Structure - Menus and click the add menu button:
Now let's add a link to the menu, and for this we will create an article
If you go to the article creation page, then there you will see that you have no way to add a link to our new menu. In order to add a link to this menu, you need to add the ability to add articles to this menu in the setting of the content type Article:
We go into editing the content type. Article and add our menu there:
Now, when creating an article, we can select our menu:
Now that we have a menu with a link, let's display it in blocks:
Now our menu is displayed on all pages.