What is the purpose of displacement maps in 3D materials?

Displacement maps in 3D materials primarily serve to add physical depth and surface detail by modifying the geometry of a 3D model. They function by using grayscale values to adjust vertex positions—lighter areas push the surface outward, while darker areas pull it inward, effectively mimicking real-world textures like bumps, grooves, or uneven surfaces. For practical use, testing with simple grayscale images helps observe how different values influence surface shape, making them accessible even for beginners.