ditto

Copy files and folders.

Syntax
     ditto [options] Source_file  Destination_file

     ditto [options] Source  Destination_folder

     ditto -x [options] Source_Archive  Destination_folder

     ditto -c [options] Source  Destination_archive

     Where Source = a file, folder or archive.

Options
     -c   create an archive at the destination path.
          Use a file extension, .zip, .cpio or .cpgz (for Compressed CPIO archives)

     -v   Print a line of output for each source folder copied.

     -k   Instead of CPIO, assume PKZip archives.

     -V   Print a line of output for every file, symbolic link, and device copied.

     -x   the first source is an archive to extract.

     -X   When copying one or more source folders, do not descend into
           folders that have a different device ID.

     -z   -x implies -z.  CPIO archives should be compressed.  Uncompressed
          data flows through the decompressor unmodified.

     --keepParent
          The parent directory of src should be embedded in Destination_archive.
          --keepParent only applies to the creation of archives.

     --arch arch
          Copy thin multi-architecture binaries ("fat binaries") to the specified
          architecture. If multiple -arch options are specified then the
          resulting destination file will be multi-architectural containing
          each of the specified architectures (if they are present in the
          source file).  arch should be specified as "ppc", "i386", etc.

     --bom bom
          If this option is given then only files, links, devices, and folders
          that are present in the specified BOM file are copied.

     --rsrc
          Preserve resource forks and HFS meta-data.  ditto will store this
          data in Carbon-compatible ._ AppleDouble files on filesystems that
          do not natively support resource forks.

     -rsrcFork
          synonym for --rsrc

     --sequesterRsrc
          ditto will preserve resource forks and HFS meta-data in the directory
           __MACOSX within PKZip archives.

Unlike cp -R, if the destination folder already exists, the existing contents will be merged with the contents of the folder being copied.

Examples

Copy the "Documents" folder to "Documents backup".
ditto Documents "Documents backup"
quotes are needed because of the space in the folder name.

To also preserve the Mac resource forks, type and creator codes use:
ditto -rsrcFork Documents "Documents backup"

“The Borgesian meta-library contains a copy of every book ever written, but my dream-artifact is already, and always, every book ever written, on demand” - William Gibson

Related macOS commands:

cp - Copy files
dd - Data Duplicator - convert and copy a file.
install - Copy files and set attributes.
mv - Move Files.
tar - store or extract files to an archive (allows symbolic links to be copied as links.)