A USB hub is a device that plugs into a single USB port and provides several additional ports, letting you connect more accessories than a computer or laptop has built in ports for. Hubs range from simple, palm sized units with a handful of USB-A ports to larger docking style hubs with many different connector types.
Hubs can be bus-powered, drawing all their electricity from the host port, or self-powered, using their own power adapter to supply more current to connected devices. A bus-powered hub is convenient for low power accessories such as keyboards or flash drives, while a self-powered hub is generally needed for power hungry devices such as external hard drives.
Connecting hubs to each other, known as daisy chaining, is possible but has practical limits on depth and shared bandwidth, since all devices behind a hub share the speed of the single upstream connection. See our guide to hubs and docks for buying advice.
