Sometimes you need to temporarily store information per same user, which means handling his session data, in previous version of drupal it was easy and more like handling it in PHP programming, but with drupal 8, since the desire was to do everything in OOP strategy it changed.

This article will review some of the options to handle session date which are available on drupal8.

First lets remember how it was done with drupal7: using the $_SESSION in module file during the hooking implementation

In Drupal 8 there's two services to handle session data: