I understood the concept of synchronising files of at least 2 directories. But what kind of files was it talking about? Is it all files in general, or just the files that we can physically see with the "dir" command? Apart from files that can be publicly seen with "dir", are we also supposed to consider synchronising hidden files, system files, files with no extensions, and files inside of sub-directories as well (or just the main outer directory)? Thank you!