Glare can seriously impair visibility: it reduces visual performance (disability glare) and visual comfort (discomfort glare). A distinction needs to be made between direct and reflected glare: direct glare is caused by luminaires or other surfaces with excessively high luminance, e.g. windows. Reflected glare is caused indirectly by light reflecting from shiny surfaces.
Glare is limited by shielding the source of glare and using less reflective materials.