\Header{help}{Documentation}
\alias{?}{help}
\keyword{documentation}{help}
\begin{Usage}
\begin{verbatim}
help(topic, offline = FALSE, package = c(.packages(), .Autoloaded),
     lib.loc = .lib.loc, verbose = .Options$verbose,
      htmlhelp = .Options$htmlhelp)
?topic
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\texttt{topic}] a name or character string on which documentation is
sought (but \emph{not} a variable containing a character string!).
\item[\texttt{offline}] a logical indicating whether documentation should be
displayed on-line to the screen (the default) or hardcopy of it
should be produced.
\item[\texttt{package}] a name or character vector giving the packages to look
into for documentation.  By default, all packages in the search path
are used.
\item[\texttt{lib.loc}] A character vector of directory names of \R\ libraries.
Defaults to all libraries currently known.
\item[\texttt{verbose}] logical; if \texttt{TRUE}, the file name is reported.
\item[\texttt{htmlhelp}] logical (or \texttt{NULL}).  If \texttt{TRUE} (which is the
default after \texttt{\Link{help.start}} has been called), the HTML
version of the help will be shown in a browser.
\end{ldescription}
\end{Arguments}
\begin{Description}
These functions provide access to documentation.
Documentation on a topic with name \texttt{name} (typically, an \R
object or a data set) can be printed with either \texttt{help(name)} or
\texttt{?name}.
In the case of unary and binary operators and control-flow special
forms, the name may need to be be quoted.

If \texttt{offline} is \texttt{TRUE}, hardcopy of the documentation is
produced by running the LaTeX version of the help page through
\texttt{latex} (note that LaTeX 2e is needed) and \texttt{dvips}.
Depending on your \texttt{dvips} configuration, hardcopy will be sent to
the printer or saved in a file.  If the programs are in non-standard
locations and hence were not found at compile time, you can either set
the options \texttt{latexcmd} and \texttt{dvipscmd}, or the environment
variables \texttt{R\_LATEXCMD} and \texttt{R\_DVIPSCMD} appropriately.
The appearance of the output can be customized through a file
\file{Rhelp.cfg} somewhere in your LaTeX search path.\end{Description}
\begin{Note}
The help files can be many small files. On some file systems it is
desirable to save space, and the text files in the \file{help} directory
of an installed package can be zipped up as a zip archive
\file{Rhelp.zip}. Ensure the files \file{AnIndex} and
\file{00Titles} remain un-zipped.  Similarly, all the files in the
\file{latex} directory can be zipped to \file{Rhelp.zip}.\end{Note}
\begin{SeeAlso}
\texttt{\Link{help.start}()} which opens the HTML version of the \R
Manual;
\texttt{\Link{library}()} for listing available packages and the
user-level objects they contain;
\texttt{\Link{data}()} for listing available data sets;
\texttt{\Link{methods}()}.

See \texttt{\Link{prompt}()} to get a prototype for writing \texttt{help}
pages of private packages.\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
help()
help(help)		# the same

help(lapply)
?lapply			# the same

help("for")		# or ?"for", but the quotes are needed
?"+"

help(package = stepfun)	# get help even when it's not present

data()			# list all available data sets
?women			# information about data set "women"

topi <- "women"
help(topi) ##--> Error: No documentation for `topi'
\end{ExampleCode}
\end{Examples}

