A register can contain a rectangle instead of lines of text. The rectangle is represented as a list of strings. See Rectangles, for basic information on rectangles and how to specify rectangles in a buffer.
Copy the region-rectangle into register r
copy-rectangle-to-register). With a numeric argument, delete it
Insert the rectangle stored in register r (if it contains a
The C-x r i r command inserts linear text if the register contains that, or inserts a rectangle if the register contains one.
See also the command
sort-columns, which you can think of
as sorting a rectangle. See Sorting.