An interactive document is a file that contains widgets and outputs. After writing a report, you can launch it as an app with the click of a button.
You can use Shiny widgets and outputs in R Markdown to create interactive documents. Embed Shiny componenets in R Markdown files to create interactive reports or slideshows. The resulting report is a complete Shiny app.
Reactive output can also be included in your documents by using
render* functions. R Markdown includes the rendered output in the result of the code chunk. The output then behaves like rendered output in a standard Shiny app, and automatically updates whenever you change a widget value or reactive expression that it depends on.
For more information on creating interactive documents using Shiny, see the Interactive Docs Shiny article.