There are many special object types within R that are designed to make it easier to analyze data. Functions in R can be polymorphic—that is to say, they can respond to different data types in different ways in order to produce the output that the user desires. For example, the plot() function in R responds to a wide variety of data types and objects, including single-dimension vectors (each value of y plotted sequentially) and two-dimensional matrices (producing a scatterplot), as well as specialized statistical objects, such as regression models and time series data. In the latter case, plots that are specialized for these purposes are produced.

As with the rest of this introduction, don't worry if you haven't written functions before, or don't understand object concepts and aren't sure what this all means. You can produce great applications without understanding all these things, but as you do more and more with R, you will start to want to learn more details about how R works and how experts produce R code. This introduction is designed to give you a jumping-off point to learn more about how to get the best out of R (and Shiny).