Lesson 4: Flags and Hidden Files

`ls` has power modes. After the command you add a "flag" — a small letter with a dash — and it changes the behaviour. We meet `-l` (full detail) and `-a` (show hidden files). This is the idea of flags, which follows us in every command.

A flag is like a button on the remote: the same command, but you tell it to behave a bit differently.

Flag: A short option (like -a) that changes how a command behaves
Hidden file: A file whose name starts with a dot, hidden by default
Long format: The ls -l view with permissions, owner, size, and date