“literate programming” – integrate code with comments about code, output, and plots. • Contain three components: • Header • Body • Code chunks • Can render the raw file into pretty version (“knitting”) – pdf, html, or word document • Then can push to Rpubs.com as way to share with other people • Can also create interactive reports with Shiny (e.g., https://mlewis.shinyapps.io/xtmem_SI/)