types of plugs and receptacles are specified for USB:
A Type and B Type. The shielded cable connector will
be 4 positions with gold-plated contacts---2 for single
on 2mm centerline, 2 for power on 2.5mm centerline.
Type Plug used for those devices (keyboard, mouse,
joystick etc...) on which the external cable is permanently
Type Plug used for those devices (printer, scanner,
modem etc...) that requires an external connector,
so that USB cabling is detachable.