- A USB hub allows you to connect multiple devices using Universal Serial Bus technology to a single USB port. The USB controller inside your computer can handle up to 127 USB devices, but computers usually only come with 2 to 10 USB ports. You can daisy-chain multiple USB hubs, but only the first one can be bus-powered, meaning that it draws its power from the computer and does not have a separate power injector.
- The core of a USB hub consists of USB ports connected to a circuit board. Most hubs have an integrated controller dedicated to the devices you connect to the hub. USB hubs are available in any USB speed standard. A device plugged into a USB hub will always operate at the slowest speed in its communications chain, whether that's the device itself, the hub or the computer into which the hub is plugged.
- Your USB devices plug into the downstream ports on the USB hub. The hub's upstream port connects to your computer. Data is passed from the device through the hub to the computer and back in packets. All USB communication is initiated from your computer, where your computer's nternal "root hub" sends packets out through your external hub's controller and into your device. Depending on the device and its state, those packets may direct your device to send packets along the return path to the computer.
