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. R provides a wide variety of statistical (linear and nonlinear modelling, classical statistical tests, time-series analysis, classification, clustering, ...) and graphical techniques, and is highly extensible. One of R's strengths is the ease with which well-designed publication-quality plots can be produced, including mathematical symbols and formulae where needed. R is highly extensible and has many user-submitted packages for specific functions or specific areas of study such as bioinformatics, ecological models, population dynamics, analysis of spatial data, and phylogenetis. Packages can be browsed by CRAN Task Views. These views may be of interest: Analysis of Ecological and Environmental Data, Statistical Genetics, Phylogenetics, Especially Comparative Methods, and Analysis of Spatial Data. There are several graphical user interface (GUI) packages that can simplify the use of R, including Tinn-R, R Commander, and SciViews.