R for Statistical Computing & Graphics
R is a free software environment for statistical computing and graphics. It compiles and runs on a wide variety of UNIX platforms, Windows and MacOS.
You can download and install the current Windows version of R (has been released on October 31st 2016) by clicking on the link below. You can either run the program, or save the program to your computer and then run it to install R. When installing, you can probably just accept the default settings.
RStudio is a set of integrated tools designed to help you be more productive with R. It includes a console, syntax-highlighting editor that supports direct code execution, and a variety of robust tools for plotting, viewing history, debugging and managing your workspace.
RStudio is available in open source (Free) and commercial editions and runs on the desktop (Windows, Mac, and Linux) or in a browser connected to RStudio Server or RStudio Server Pro (Debian/Ubuntu, RedHat/CentOS, and SUSE Linux).