The Editor module is included in Drupal 8 core.
The Text Editor module provides a framework to extend the user interface on text fields that allow HTML input. Without Text Editor module, fields accept only text where formatting must be typed manually, such as entering a
<strong> tag to make text bold or an
<em> tag to italicize text. The Text Editor module allows these fields to be enhanced with rich text editors (WYSIWYGs) or toolbars, which make entering and formatting content easier.
Issue Queue for 8.x