How is registration/authorization implemented in Yii2?

Question

Yii

Good day to all. The question is abstract.
I started learning yii2, before that I learned to write only in pure php. Actually, the question is, according to what prince does registration and / or authorization work on Yii2?
For example, in pure php, when registering, an SQL request is made and the user is entered into the database. During authorization, this entered data is checked for a match, and if it matches, then we are logged in.
How is it all with Yii2? I saw a bunch of examples of how to do it in terms of code, but I did not find any interpretations, the principle of operation.

Answer 1

in Yii2 everything is done for us , it
remains only to use them
in detail here or here
or a video tutorial

Answer 2

in Yii2, authorization data is written to the session. Requests to the database will only be made if user data is needed (for example, display a nickname).