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, it allows you to easily strip formatting when pasting text into your content with the Paste as text button (), and you can also insert special characters like ¼, ½, ¾, ©, €, ™ etc., with the Special character button ().
The Classic Editor it is perfect for when you have text heavy content and just need a simple editing interface.
Since the the Block Editor is now the default editor within WordPress you’ll need to install the Classic Editor plugin to be able to use the old (TinyMCE) Classic Editor. The Classic Editor plugin will allow you to disable the new Block Editor and instead, will provide you with the same editing interface that you've been using prior to WP 5.0. The Classic Editor plugin can be downloaded from the Plugin Directory on the WordPress.org website, or you can install it directly onto your site using the Plugins > Add New menu option and then typing in ‘Classic Editor’ (without the quotes) in the Search plugins… field.