R is an open source system widely used in statistics, bioinformatics and finance field etc. It's
data structure and working environment are perfect for analysis of large sized data. It's easy and quality plotting really set it apart from most other programming languages.
Many classical and modern statistical algorithms are implemented.
A lot of packages in various fields make it more powerful. The R Project home page is http://www.r-project.org.
R packages address is (http://CRAN.R-project.org).
RStudio is a popular IDE (integrated development environment) for R.
Many books about R are freely available at http://cran.r-project.org/doc/contrib/.
» R Installation and Quick Start