Normal maps are a type of texture used in 3D graphics to simulate surface details without increasing the polygon count. They store information about the direction of surface normals, allowing for the illusion of depth and complexity on flat surfaces. This technique enhances visual realism in video games and animations by creating the appearance of bumps, grooves, and other intricate features. By using normal maps, artists can achieve high-quality visuals while maintaining performance efficiency. They are commonly used in conjunction with other textures, such as diffuse maps and specular maps, to create a more complete and realistic representation of 3D objects.