Overexposed areas with no detail — pure white, unrecoverable. Happens with excess light or wrong exposure metering; often lost in post.
Burned out are those damned white areas in the frame that have no detail anymore — highlights that have been overexposed to the point where the sensor data is simply gone. You look at the monitor, and suddenly there's just white: no structure, no retouching possible, nothing to salvage in the edit. This is every DoP's nightmare because it means: this information no longer exists.
The causes are trivial but insidious. Too much available light hits the sensor, the ND filter is too thin or forgotten, the aperture is set incorrectly, or you haven't metered the fill lights properly. When shooting digitally, this happens faster than it used to with film — the sensor is unforgiving, the curve drops off brutally steeply. Particularly insidious: with modern cameras, the live image often appears beautified by internal LUTs, the monitor deceives you. True monitoring via external recorders or a verified waveform is your only protection.
Practically, you combat burn out with multiple layers. First: exposure metering before the shoot, specifically checking your highlights — don't aim for middle gray. Second: ND filter calculation is correct before the first scene rolls. Third: use the exposure menu if the camera offers one — some models show you overexposed areas live, as if the camera were blinking. Fourth: use reflectors and flags to control hot spots, especially with high-contrast scenes.
In the edit, burned-out areas are practically impossible to save. At best, you can try to make the white area more tonal with color grading, but the image information is genuinely gone — not like underexposed shadow areas where data still slumbers in the RAW. Therefore, prevention is everything. Triple-check on set — that's your only real control. And if you're working with LOG material: the LOG preview can also deceive you. Don't trust the live image alone; work with actual metering curves.