Normal maps are a type of texture used in 3D graphics to create the illusion of detailed surface features without increasing the polygon count. They store information about the direction of surface normals, which helps simulate bumps, grooves, and other small details on a model. This technique allows for more efficient rendering while maintaining a high level of visual fidelity. In video games and computer graphics, normal maps are often used alongside other textures, such as diffuse maps and specular maps, to enhance realism. They are commonly created from high-resolution models and applied to lower-resolution versions, making them essential for optimizing performance in real-time applications.