Objects that block light are called opaque objects. Opaque objects do not allow light to pass through them. Some examples of opaque objects include:

1. Wood

2. Metal

3. Stone

4. Concrete

5. Cardboard

6. Plastic

7. Fabric

8. Paper

9. Human body

10. Trees

11. Books

12. Walls

13. Buildings

14. Mountains

15. Rocks

These objects either absorb or reflect light, preventing it from passing through. In contrast, transparent objects allow light to pass through them almost completely, while translucent objects allow only some light to pass through.