USB is the Universal Serial Bus, used for plugging in many devices, such as printers and keyboards.
Ports are the various places where you can plug things in to your Mac: a keyboard, scanner, printer, speakers, a joystick — whatever.
Use the built-in Help, available from any application on your Mac. Look in the menu bar for ‘Help’.
Finder pop-up windows were handy in Mac OS 9.
Hold down Option while you close one window and all open windows for that application will close.
How to implement a Eudora Applescript to mark messages in Eudora as unread.