readme.md

Markdown document Reference

An .md file contains a document in Markdown. The plain-text format marks structure with simple characters: number signs for headings, stars for emphasis, hyphens for lists. Tools convert Markdown to HTML for display. Software projects write their README files in this format. Code hosting sites render .md files directly.

A file extension is only a part of the file name. It does not give a guarantee about the format or the content of a file. But on Windows, the extension selects the program that opens the file.