How road sign reflectors work

I watch a lot of explainer videos, and Technology Connections makes some of the best. The host is knowledgeable, explains things clearly, and is funny, to boot. In this episode, he talks about retroreflectors, which are reflective surfaces that send light back to its source with very little scattering. This is very useful for road signs where the only source of Illumination is a car's headlights.