## 12.2 What is Markdown?

Markdown is a lightweight language that can be used to write fully-formatted documents. It is plain-text and uses a simple set of rules to produce rather sophisticated output - we love it!

It is easy to format headings, bold text, italics, etc. Within RStudio there is a Quick Reference guide (Figure 12.2) and links to the RStudio cheatsheets can be found in the Help drop-down menu.

Markdown exists independent of R and is used by a range of techies and alike. A combination of Markdown (which is text with special characters to indicate desired formatting) and R code within it (usually to produce tables and plots) is called R Markdown. R scripts have the file extension .R, Markdown documents have a file extension .md, therefore, R Markdown documents are .Rmd.