Markdown is a lightweight markup language with plain text formatting syntax designed so that it can be converted to HTML

Markdown is a lightweight markup language with plain text formatting syntax designed so that it can be converted to HTML and many other formats using a tool by the same name.[8] Markdown is often used to format readme files, for writing messages in online discussion forums, and to create rich text using a plain text editor.

https://en.wikipedia.org/wiki/Markdown