What is normal map in 3D modeling Substance Painter?

In 3D modeling with Substance Painter, a normal map is a texture that adds surface details (e.g., bumps, scratches, fabric texture) to low-poly models without increasing polygon count—key for efficient, realistic results. It works by storing surface normal directions in RGB values, telling the render engine how light should reflect off the surface. This creates the illusion of depth and detail without extra geometry, perfect for enhancing low-poly assets. For beginners, use the "Normal" channel in the Layer Stack to paint or import simple details (like wood grain) and test how it affects light and shadow—an easy way to start using normal maps effectively.