Drupal 8.x

hi,
in drupal 8 does "user interface" has a special meaning ?
Is it relative to some classes, some uml concept ?
Thanks.

what the difference of two hooks in the "hook_theme_suggestions_HOOK_alter(array &$suggestions, array $variables)"?

thanks!

The examples are from Drupal7, but the conversation is for Drupal8 or Drupal9, as the Drupal7 boat has sailed.

Hello!

I just downloaded Drupal with the aim of creating a small searchable database. For this task I assume Views would be the best tool?

I want to create entries that contain:

Country (outputted by list, or by auto-complete while user types)
Name of persons (I want them to auto-complete, based on previous entries)
Date (Year, Month, Day)
Tags (These auto-complete, based on previous entries)

Could anyone advice me which modules I should use for this purpose? I tried searching but could not find the appropriate modules.

I want to develop a custom application but, I want to use a CMS as not to reinvent the wheel. I'm leaning toward Drupal right now, although I have read that Drupal 8 will be better as far as developing custom applications. At work, I am used to using a custom built CMS with a lot of features related to creating custom applications. What are your experiences with developing applications on top of Drupal?

Which of the following books would you recommend?

Drupal 7 Module Development - Butcher, Garfield, et. al.

Now I "learning" Drupal 8. I need next function, but now know how better to do it.
I have next nodes structure:

• node1 (parent=NULL)
  • node2 (parent=node1)
    • node3 (parent=node2)
  • node4(parent=node1)
• node5 (parent=NULL)

I need to have view page with structure like this. How I can add field for "child" nodes?

e.g. in Drupal 7 I can use "views field view" module and add "child" view with "parent NID" contextual argument, and got something like next:

• MainView :