[github] What is the difference between README and README.md in GitHub projects?

I've noticed some GitHub projects have not only a README file, but also a README.md file.

What is the difference between these files? I know README serves also as introductory text in the project repository page but I have no idea what README.md does.

.md stands for markdown and is generated at the bottom of your github page as html.

Typical syntax includes:

Will become a heading
==============

Will become a sub heading
--------------

*This will be Italic*

**This will be Bold**

- This will be a list item
- This will be a list item

    Add a indent and this will end up as code

For more details: http://daringfireball.net/projects/markdown/

.md extension stands for Markdown, which Github uses, among others, to format those files.

Read about Markdown:

http://daringfireball.net/projects/markdown/

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

Also:

http://github.github.com/github-flavored-markdown/

README.md or .mkdn or .markdown denotes that the file is markdown formatted. Markdown is a markup language. With it you can easily display headers or have italic words, or bold or almost anything that can be done to text