What does dynamic range mean to a photographer?

Can you explain what dynamic range means to a photographer? That is, an artist who understands how to capture light and make an image from it, but doesn't have a clue what SNR means, or what an ADC is... and probably wouldn't get it if you tried to explain. Please refer to both DR in the scene and DR in the image, and how they relate to each other.

If I can get that I'll follow with another more specific question. Thanks.