Light Pollution Reduction

When this was written, HID lamps were normal for exterior lighting. Lamp term doesn't apply to LEDs but the intent is the same.  Anything that blocks the light from shining where we don't want the light. 

This can be part of the fixture.  "Cutoff" rating to block the light from shining up into the sky.  Or "House-side shield" to block light shining onto the neighbor's property.

Or it can be structure that blocks the light, like a canopy or wall.