R is an open source, programming lingua franca of statistics. It was created by Ross Ihaka and Robert Gentleman at the University of Auckland, who wanted a language that was better suited to statistical computing and easier to use than comparable software designed by computer scientists.
In addition to being a programming language, R is also an environment for interactive data analysis. Its powerful metaprogramming capabilities allow for magically succinct and concise functions. It can also integrate with high-performance programming languages like Fortran, C, and C++. These combined attributes provide an excellent environment for designing domain-specific languages.
Ross Ihaka describes R as "a real demonstration of the power of collaboration". R has a fantastic community of both users and developers, who contribute to a massive (and rapidly growing) collection of packages for importing, manipulating and visualising data, as well as cutting edge methods for statistical modelling and machine learning.
Learn more on r-project.org!