It's all of these:
-r, --recursive recurse into directories
-l, --links copy symlinks as symlinks
-p, --perms preserve permissions
-t, --times preserve modification times
-g, --group preserve group
-o, --owner preserve owner (super-user only)
-D same as --devices --specials
--devices preserve device files (super-user only)
--specials preserve special files
-H, --hard-links preserve hard links
-A, --acls preserve ACLs (implies -p)
-X, --xattrs preserve extended attributes
It's perfect for backups. My "default" set of switches is
-avzP - archive mode, be verbose, use compression, preserve partial files, display progress.
Note: Invariably when the descriptions say "preserve", it means make the destination be like the source.