Rendering Intent
The strategy chosen for handling colours that fall outside the destination gamut during a colour space conversion.
In depth
Four intents are defined — perceptual, relative colorimetric, saturation and absolute colorimetric — and only the first two matter for photographs. The right choice depends on how much of the image is out of gamut: a mostly in-gamut file is better served by relative colorimetric, a heavily saturated one by perceptual.
Examples in practice
Soft proofing the same file with both photographic intents reveals which preserves the flower's petal detail better.