The Classic Editor, also known as the Visual Editor or TinyMCE Editor, is the default editing experience that came with WordPress prior to version 5.0. Although it's simple in its nature, it has powerful word processing capabilities.
Much like a regular word processor, it has toolbar buttons that allow you to Bold () or Italicize () text, add Headings () or bullet points ( ) or even change the colour of your text. You can even use most of the basic keyboard shortcuts used in other text editors.
On top of word processing functionality it's easy to embed content such as Twitter Tweets, YouTube and Vimeo videos, and dozens of other types of content. It's also extremely easy to add images and other media into your content.
The Classic Editor it is perfect for when you have text heavy content and just need a simple editing interface.