Markdown is a text file optionally with .md or .markdown extensions. It can be converted to HTML. Markdown syntax is on GitHub. Any text editor works for Markdown. Sublime Text has a preview plugin to display rendered Markdown. Some online Markdown editors are Markable.
Markdown isn’t a file format. It subtly adds information to plaintext. Markdown is metadata, not formatting. No confusion if someone finds Markdown syntax in a text file – it’s a bonus. “.text”, “.txt” extensions make sense.
No one syntax would make all happy. Gruber avoided curly braces in Markdown to reserve them for extensions.
CommonMark is a standardization. Filename extensions are .md and .markdown. The Internet media type is text.
Text files with Markdown dialects have .md or .MARKDOWN extensions. They are saved as plaintext that uses Markdown formatting like indentations and headers. MD files convert to HTML. John Gruber released Markdown.
No official extension exists. Plain text files with .md extensions work. Different extensions: .markdown, .md.
Markdown files open in text editors. Probably not convertible.
Markdown files review easily in text against revisions. GitHub README.markdown has source code readme. “Markdown” program converts Markdown to HTML.
Full name is Markdown Documentation Format. John Gruber defined it. Compatible software installs on Linux, Mac, Web, Windows. It is a Developer File.
Best extension is .markdown. GitHub uses .md. @drdrang uses it. I’ll stick to .markdown – more descriptive, not 8.3 limited.
Projects use MARKDOWN for documentation. Frameworks use it for sources. .md, .mdown, .markdn also work. Open with Sublime.
Visual Studio Code
Notepad++