* R is a free software environment for statistical computing and graphics. It runs on a wide variety of UNIX platforms, Windows and MacOS. This R Wiki is dedicated to the collaborative writing of R documentation.
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R comes with several official manuals and FAQs. These should be your primary source of information. Note also that the main location for general questions about R is the R-Help mailing list (but please make sure to read the posting guide before posting a question there!). Finally, R Journal is a refereed journal dedicated to R.
Personal note: I have some difficulties with the statement that the official manuals should be your primary source of information. They are the authoritative source of information, but not necessarily the first. Due to their nature, I can’t always recommend the built-in help or the official manuals for the casual user. Too often the Help tests seem to be written to be technically correct rather than helpful, and aimed at experienced users rather than the novice or the casual user. This is not a problem, as long as you are aware of it.
I found ordinary books to be the most helpful source of information for novice programmers and I can particularly recommend:
The R-Help mailing list can give excellent answers, but due to the high calibre of respondents it can be intimidating, (and off-putting). This unfortunately is done on purpose so as to regulate the amount of traffic (not unreasonable since you are in fact soliciting unpaid advice from highly qualified specialists, and making this display of professional courtesy too attractive will inevitably lead to people swamping the list and wasting its bandwidth).
In addition I can’t but feel that many questions are a waste of time for most of those who respond. What is needed (in my opinion) is a more relaxed forum where people can ask more “stupid” questions without being told to “RTFM” (in more or less polite ways), and where less highly qualified people will respond. My recommendation for programming questions with R is:
Note however that Google has indexed the Stackoverflow forum, and that a Google search will generally get you there faster than using the forum’s own search engine.