The next time you go out, do observe these things and see if they reflect light or not.
The reflectors that you find on the road are called Road Studs.
You might have noticed workers wearing special kinds of clothes for their safety. These cloths also have reflectors on them.
You can also find reflectors on your bicycle, at its rear and its tyres.
If you notice the traffic signboards, you will notice that even they have reflectors on them so that the vehicles can see them easily.