Command, Option, Control and Shift on a Mac keyboard
Command (⌘) is used in many app commands. Option (⌥) adds alternate actions or characters. Control (⌃) is distinct from Command, and Shift (⇧) changes case or modifies a command. Test left and right modifiers separately when your keyboard has both.
Common Mac keyboard shortcuts for everyday work
In many Mac apps, Command-C copies, Command-V pastes, Command-Z undoes and Command-A selects all. Command-Tab switches apps, while Command-Space commonly opens Spotlight. Assignments can be changed and application behavior can differ.
Why browser shortcuts interrupt keyboard tests
Command-W commonly closes a tab and Command-L focuses the address bar. The page cannot reliably cancel every operating system or browser command. Test modifiers by themselves and use ordinary letter groups for rollover checks.
Check modifier remapping on external Mac keyboards
If Command and Option feel swapped on an external keyboard, review modifier-key settings in macOS. A browser displays the delivered event; it cannot tell whether the operating system or keyboard firmware remapped the original key.