R Markdown = R + Markdown

• R Markdown is an authoring format that enables easy creation of dynamic documents, presentations, and reports from R.
• Markdown is a text-to-HTML conversion tool to write quick HTML code

Here is the input/output flow

1. R Markdown .Rmd file. R runs all code and generates all outputs, yielding an internally generated
2. Markdown .md file. All Markdown code is formatted, yielding
3. Either a
   1. HTML file
   2. PDF file
   3. Word file (yuck)

The most common example of a .md Markdown file is the README.md intro page to any GitHub repo. For example, the NY Times' iOS photo viewer:

• Go to the repo page and look at the page
• Click on README.md
• Then click on RAW to see the Mardown source code

• Markdown Reference: Menu bar -> Help -> Markdown Quick Reference
• R Markdown Debugging