There are four working panes in RStudio:
Source code pane This pane is where scripts are written/loaded and displayed. It has syntax highlighting and auto completion, and allows you to pass code line by line, as selections, or as a whole.
R console pane This is where commands are executed and is essentially what the base R console looks like, except better! The console has syntax highlighting, code completion and interfaces with the other RStudio panes.
Workspace/History pane The workspace tab displays information that is usually hidden in R, such as loaded data, functions and other variables. The history tab stores all the commands (lines of code) which have been parsed through R.
Everything else panefn10 This pane includes the files tab (lists all files in current working directory), the plots tab (any plots/graphs), packages tab (installed packages, and the help tab (inbuilt html help system).
fn10. For lack of a better name… ↩