Markdown is a simplified text formatting syntax. There are many like it, but it appears to be the one gaining the most traction. The "original" syntax is almost too-simple though, and there are a bunch of extensions, too.
As I've come to utilize markdown and pay more attention to others who do as well, I've taken note that some people are adding filename extensions to indicate that the file is formatted with markdown.
So far, I've seen:
I like md the best because it is short, but it might be misleading as it doesn't explicitly yell "This file is formatted with markdown!".
Similarly, I also dislike .markdown the most because it is so long.
Personally, I've been using the ".txt" extension because at heart, markdown files are truly .txt files. Or maybe because back in the dial-up days I used to belong to a bunch of BBS's which hosted tons of cool "txt files"!
I think I'll probably start trying out .md.txt. I like the way extensions can be chained together, like .tar.gz or .tar.bz2, and then merged into a shorter one, like .tgz and .tbz.
What do you think is the best filename extension for markdown formatted files? Feedback welcomed and appreciated!