"R is an open source programming language and software
environment for statistical computing and graphics. It consists of
a language together with a run-time environment with a debugger,
graphics, access to system functions, and scripting.
"The R language is extremely popular for developing statistical
software, and is also frequently used as an analysis tool amongst
data miners. R is an implementation of the S programming language,
developed by Bell Laboratories, adding lexical scoping semantics. R
offers a wide variety of statistical and graphical techniques
including time series analysis, linear and nonlinear modelling,
classical statistical tests, classification, clustering, and more).
Combined with a large collection of intermediate tools for data
analysis, good data handling and storage, general matrix
calculation toolbox, R offers a coherent and well developed system
which is highly extensible.
"Many statisticians use R with the command line. However, the
command line can be quite daunting to a beginner of R. Fortunately,
there are many different graphical user interfaces available for R
which help to flatten the learning curve."