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. 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 - wikipedia 
Previewing markdown when developing locally is a common problem that many markdown editors (such as HackMD look to solve.
Markdown is a: > DSL for creating HTML documents that are still readable as plain text.
# Github Flavored Markdown
Github has a variant called Github Flavored Markdown which adds features.
- github-markdown-preview: A ruby gem to start a server which allows one to preview markdown file changes automatically. github
- GFMD cheatsheet github gist
- Autolinked references github
# See also