Project created and used by RStudio, an open source IDE for the R programming language; contains project information used to customize the behavior of RStudio, such as loading RStudio settings and restoring previously edited source documents into editor tabs; also used to indicate whether to load the .RHISTORY file for use in the RStudio History pane and the .RDATA file in the project's main directory.

RStudio introduced projects in version 0.95 in order to make managing multiple directories more straightforward. You can create an RPROJ file in a new directory or an existing directory that already has R code and data. You can also create the project file by cloning a version control repository, such as Git or Subversion. NOTE: The file extension used by an RStudio project appears as ".Rproj". You can double-click the RPROJ file to directly open the project.