Driver
A driver is a software program with the purpose of connecting hardware to a software interface. You will know drivers from messages such as: "Installing driver for device X", "Update your drivers to a newer version", and the worst of all "No suitable driver found."
Tech N00B: Why can't I use my new soundcard.
Tech G0D: Have you installed the drivers?
Tech N00B: Why would I need drivers?
Tech G0D: Talk to the hand