R can be described as a language and environment that allows for statistical computing and graphics. It is a GNU project that is similar to the S environment and language which were developed at Bell Laboratories (formerly AT&T) by John Chambers and his colleagues. R can be considered a different implementation for S. However, most code written for S runs unchanged under R.
R is extensible and offers a variety of statistical (linear, nonlinear modelling and classical statistical tests, time series analysis, classification, clustering and graphic techniques. Research in statistical methodology is often done using the S language. R offers an Open Source route to participate in this activity.
R's strength is its ability to produce well-designed plots of publication-quality quality, including formulae and mathematical symbols. While R has taken great care to avoid making mistakes in graphics design, the user still retains complete control.