It's all of these:
--recursive recurse into directories
--links copy symlinks as symlinks
--perms preserve permissions
--times preserve modification times
--group preserve group
--owner preserve owner (super-user only)
-D same as
--devices preserve device files (super-user only)
--specials preserve special files
--hard-links preserve hard links
--acls preserve ACLs (implies
--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.