How do I create a copy of a directory in Unix/Linux?

I want to recursively create a copy of a directory and all its contents (e.g. files and subdirectories).

The option you're looking for is -R.

cp -R path_to_source path_to_destination/

• If destination doesn't exist, it will be created.
• -R means copy directories recursively. You can also use -r since it's case-insensitive.
• To copy everything inside the source folder (symlinks, hidden files) without copying the source folder itself use -a flag along with trailing /. in the source (as per @muni764's / @Anton Krug's comment):

cp -a path_to_source/. path_to_destination/