In addition to the USB protocol, there is a second specification for the USB host controller, the piece of hardware on the PC to which a device is connected. USB, with no descriptor, refers to low speed and full speed devices. Hi-Speed USB is used to describe high-speed USB 2.0 devices.
If you look at product packaging, SuperSpeed USB references the newest USB 3.0 devices. USB 3.0 continues to work with all of the previously defined data rates. USB 2.0 defines a new data rate, high-speed USB (480 Mbps), while maintaining support for low and full speed devices. USB 1.0 defines two different data rates, low speed USB (up to 1.5 Mbps) and full speed USB (up to 12 Mbps). The newest specification revision is USB 3.0, which specifies a maximum transmission speed up to 5 Gbps. The version number also indicates the maximum transmission speed.
The USB specifications define how the host PC and USB device communicate with each another.
USB 3.0, USB 2.0, and USB 1.0 refer to the USB specification revision number from the USB Implementers Forum. Let's understand the USB terms in that sentence. Say you see something like, 'Thanks to USB 3.0, I can connect a SuperSpeed USB thumb drive to my PC's xHCI host controller and copy files faster.'
