Questions relating to the Raspberry Pi USB ports and specific Raspberry Pi USB devices and device interaction.
The Universal Serial Bus (USB) is an industry standard developed in the mid-1990s that defines the cables, connectors and communications protocols used in a bus for connection, communication and power supply between computers and electronic devices.
The Rasperry Pi uses USB 2.0, hi-speed, full-speed and low-speed. It can interoperate with SuperSpeed USB 3.0, but will only reach hi-speed with such devices (in USB 2.0 compatibility mode).
For questions concerning power output, see first: