What is a Darlington?

yep .. it's a chip

if you want to jump from a lower powered logic circuit to a piece of moving, flashing and noisy piece of art .. then you need to use one ..

Warning! It is important to understand the damage caused to the logic circuits when large current devices are nearby.  It is usual to provide two power supplies for these kind of devices.  Look at the remote control cars to see this set up.

or .. who was he? A person.  Did he ever think they would be so cheap?