`GNU S' - A language and environment for statistical computing and
graphics. R is similar to the S system, which was developed at Bell
Laboratories by John Chambers et al. It provides a wide variety of
statistical and graphical techniques (linear and nonlinear modelling,
statistical tests, time series analysis, classification, clustering, ...).

R is designed as a true computer language with control-flow
constructions for iteration and alternation, and it allows users to
add additional functionality by defining new functions. For
computationally intensive tasks, C, C++ and Fortran code can be linked
and called at run time.