1.1 What is R and RStudio?
R is a high-level computer language that is designed for statistics and graphics. One main feature is vector program language like Matlab. It is initially written by Ross Ihaka and Robert Gentleman (Depart. of Statistics of the University of Auckland, New Zealand, and hence the name). Currently, it is a free open source software maintained by several contributors.
Compared to alternatives, SAS, Matlab or Stata, R is completely free. Another benefit is that it is open source. This means that there is no black box for everything you use. You know what you are doing. It is also freely expendable so that you can do what you want to do.
RStudio is an integrated development editor (IDE) for R. It is easier to write code using the editor.