Joomla 3 what's the mess with urls?

Question

Joomla

I installed the latest version 3.4.4 on Denver with demo data (Learning Joomla! English (GB) demo data) in which there is a category tree and materials.
Enabled CNC, redirection, renamed .htaccess, created a new material in the root (one of) category Sample Data-Articles (Alias: sample-data-articles). Well, the fact that you can’t see the url of the material from the admin panel, I’m not surprised anymore, okay, I’m looking on the site - and I find it with the address

http://joomla/using-joomla/extensions/components/content-component/article-categories/72-proba2

And there's a lot I don't understand right now.
1. it is logical to expect the url /sample-data-articles/72-proba2, why is there a lot of garbage in the url?
2. why category url

http://joomla/using-joomla/extensions/components/content-component/article-categories

does not contain a category alias (sample-data-articles), but again, contains a bunch of garbage?
3. I guess /extensions/components/content-component/article-categories is the path in joomla engine to article categories component, but using-joomla is stuff! what, in general, is the logic of forming such an url?
4. Okay, I found on the page http://joomla/site-map/articlesa link to the root category, which is Sample Data-Articles, this, again

http://joomla/using-joomla/extensions/components/content-component/article-categories

I follow it in the hope of seeing my article Prob2. I see such crumbs

You are here: Home >> Using Joomla! >> Using Extensions >> Components >> Content Component >> Article Categories

, links to 3 nested categories, no mention of Sample Data-Articles and Sample2. What is going on??

Answer 1

In Joomla, you need to create a link structure using a menu (it is not necessary to publish it).
Create a menu, name it, for example "Site Structure" and create an item in it for the "Category Blog" type with the desired alias for the selected category, for example, /articles.
Now all your posts will be available at addresses like
yoursite/articles/01-article-alias
where /articles is the alias of the category of articles, and /01-article-alias is the alias of your article
. it is necessary, observing the necessary structure, to create a menu item of the "material" type for a specific article.
From personal experience:
For a long time, at the beginning of creating a site, I create the "Structure" menu and collect the entire structure of the site there, and then to display the main menu and other sidebars I create additional menus and use menu items like "Menu item alias" in them, in this case the links will be similar to the menu "Structure". And all this will greatly simplify the creation of a sitemap using xmap