It's tough to imagine a time before USB, when connecting devices to your computer ... you plug your phone into a computer, ...

Output devices close output device A device used to output data or information from a computer, eg a monitor, printer or speakers. allow a system to present information back into the ‘real’ world.

USB 3.0 stepped power output up to 5V at 0.9A, giving us a more tolerable 4.5W. Some USB 3.0 ports that are designed for charging can supply 5V at 1.5A, or up to 7.5W.