OVEREXPOSED
Your photo is overexposed.

In the case of a digital camera, the problem is almost certainly caused by incorrect exposure settings on your camera.

In the case of a scanned image, it may be a problem with the original photo, negative or slide. Check your original photo, and if it appears to be correctly exposed then please change the settings on your scanner and rescan the image.

You may try to use an image editing program to decrease the brightness or exposure of the images, but in most cases this will not lead to satisfactory results, and you will most likely be unable to improve the shot to an acceptable standard.

Increasing the lighting during post-processing led to an overexposed rejection - Photo copyright © Thierry Deutsch

Front part of the aircraft shows blown out areas - Photo copyright © Paul Markman

The easiest way to see if a photo is overexposed is to look for blown out white areas; if you have bright white areas on your subject that don't show any more details like dividing lines, bolts or rivets your photo is most probably overexposed. If this happened during post-processing only you can easily rectify it; however if you overexposed the photo during shooting, rectifying the overexposure gets very difficult to impossible. That is why it can be of great help to shoot in RAW as by its nature the RAW version saves much more information of a photo and thus slightly overexposed images can still easily be saved in post-processing where JPEG files are already "lost" as they don't save any margin for error.