What is a .md file?

A `.md` file is a plain text file written in Markdown, a lightweight markup language created by John Gruber and Aaron Swartz in 2004. Markdown allows writers and developers to format plain text documents cleanly using simple, unobtrusive keyboard symbols, such as hash signs (`#`) for headings, asterisks (`*`) for bold or italic text, dash lines for bullet points, and brackets `[title](url)` for hyperlinking. `.md` files are universally supported because they can be opened and edited in any basic text editor (like Notepad, TextEdit, VS Code, or Obsidian). They are extensively used across the software engineering community for documentation (such as GitHub `README.md` files), web development, content management systems, static site generators (like Jekyll or Hugo), and personal knowledge management systems because they convert easily into rich HTML text while remaining human-readable in raw text format.