O for Over-Exposure
By definition, Overexposure is a condition when the photo receives more light than it should have. Causes, slower shutter speed or wide open aperture or high ISO. Effects include excessive highlights and washed out details. Some bits of the photos are recoverable, given they have been shot in RAW format (for comparison with JPEG, check here), but often, complete recovery is not possible and some compromises are done. Exposure compensation is an in body technique to control exposure issues, else, we depend on the post processing to sort things out.