R is an interpreted programming language and software environment for statistical analysis, graphics representation and reporting. R also allows integration with the procedures written in the C, C++, .Net, Python or FORTRAN languages for efficiency. R is named so after the creators Ross Ihaka and Robert Gentleman at the University of Auckland, New Zealand, and is currently developed by the R Development Core Team.
R-Studio is most commonly used for development. It provides features to run commands as well as scripts. You can install R and R-Studio from their website.
Once you have R environment setup, then it’s easy to start your R command prompt by just typing the following command at your command prompt:
> myString <- "Hello, World!" > print ( myString)  "Hello, World!"
Here first statement defines a string variable myString, where we assign a string "Hello, World!" and then next statement print() is being used to print the value stored in variable myString.
Usually, you will do your programming by writing your programs in script files and then you execute those scripts at your command prompt with the help of R interpreter called Rscript. So let's start with writing following code in a text file called test.R
# Hello World myString <- "Hello, World!" print ( myString)
You can save the above code in a file helloWorld.R and execute it at the command prompt as given below. You can also do that within the R-Studio if you want to avoid the hassles of setting up the path.
$ Rscript test.R  "Hello, World!"