What Does Local Dimming Do on a TV?

Q I have a Vizio TV, model number D48f-E0. The company’s specs say that it’s a “Full Array LED
display.” It also has a “Backlight Control” in its picture settings menu that automatically dims or brightens the backlight during viewing. Is this feature the same thing as local dimming? I’m confused here — if backlight control and local dimming are separate features, what’s the difference between them? —James Paxton, via email