The R Project for Statistical Computing

R is `GNU S’ – A language and environment for statistical computing and graphics. R is similar to the award-winning 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, …).
Find The R Project for Statistical Computing at: http://www.r-project.org