While the commercial implementation of S, S-PLUS, is struggling to keep its existing users, the open source version of S, R, has received a lot of attention in the last _ve years. Not only because the R system is a free tool, the system has proven to be a very e_ective tool in data manipulation, data analysis, graphing and developing new functionality. The user community has grown enormously the last years, and it is an active user community writing new R packages that are made available to others. If you have any questions or comments on this document please do not hesitate to contact me.
The best explanation of R is given on the R web site http://www.r-project.org and http://stat.ethz.ch/R-manual/R-devel/DOC/HTML/ . The remainder of this section and the following section are taken from the R web site.