Markdown is a lightweight markup language with plain text formatting syntax.

from Wikipedia page on Markdown

Markdown was developed by John Gruber but has spread quite rapdily into all kinds of contexts. for example:

  • a lot of WordPress or MediaWiki installations use Markdown via Plugins on the backend
  • keyonte/powerpoint-style presentations can be crafted in Markdown via the remark project

Markdown editors for macOS

  • MacDown ( open source )
  • BBEdit ( free + pay version )
  • iA Writer ( slick but super expensive, also available for Windows, Android + iPhone+iPad)