The read.table() and read.csv() functions are the most commonly used functions for reading tabular data into R. They can be used to read data from a variety of file formats, including CSV, tab-delimited, and Excel files. The readLines() function can be used to read lines of text from a file. The source() function can be used to read R code files into R. The dget() function can be used to read R code files into R. The load() function can be used to read saved workspaces into R. The unserialize() function can be used to read single R objects in binary format.
The write.table() function can be used to write tabular data to a text file or connection. The writeLines() function can be used to write character data line-by-line to a file or connection. The dump() function can be used to dump a textual representation of multiple R objects. The dput() function can be used to output a textual representation of an R object. The save() function can be used to save an arbitrary number of R objects in binary format to a file. The serialize() function can be used to convert an R object into a binary format for outputting to a connection (or file).
There are many other R packages that have been developed to read in all kinds of other datasets. These packages may be necessary if you are working in a specific area.
