Comments. USB has become ubiquitous as the way to connect our mobile devices to power sources and to other devices. There are currently seven different types of USB connectors already in use: USB 2.0 A, B, mini B and micro B; and USB 3.0 A, B and micro B. There's about to be one more: the USB Type-C.here are currently seven different types of USB connectors already in use: USB 2.0 A, B, mini B and micro B; and USB 3.0 A, B and micro B. There's about to be one more: the USB Type-C.