Getting help in R
From AWF-Wiki
As stated in Introduction to R, R has an excellent help system implemented in the core or in the respective packages, but also a very active community sharing expertise on how to implement functions, or even sharing scripts. The help for a given function or procedure can be called by using the help(function-name) function or ??function-name or ??procedure-name. The result of this code is a detailed description of the function, with the necessary arguments and also bibliography. As an example, the following code produces the help information showed below.
help(mean)