It’s all of these:
-r,--recursiverecurse into directories
-l,--linkscopy symlinks as symlinks
-p,--permspreserve permissions
-t,--timespreserve modification times
-g,--grouppreserve group
-o,--ownerpreserve owner (super-user only)
-Dsame as--devices --specials
--devicespreserve device files (super-user only)
--specialspreserve special files
It excludes:
-H,--hard-linkspreserve hard links
-A,--aclspreserve ACLs (implies-p)
-X,--xattrspreserve 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.