Clutter is the bright, confusing and excessive groupings of light sources, such as many lit advertisements signs in one place. 

At night, too many lights may generate confusion, distract from obstacles (including those that they may be intended to illuminate), and potentially cause accidents.

Clutter is particularly noticeable on roads where the street lights are badly designed, or where brightly lit advertisements surrounds the roadways. Depending on the motives of the person or organization that installed the lights, their placement and design can even be intended to distract drivers, and can contribute to accidents.