Shader programming involves writing small programs, called shaders, that run on the graphics processing unit (GPU) to control how images are rendered on the screen. These programs define the appearance of surfaces, lighting, and effects in 3D graphics, allowing for realistic visuals in video games and simulations. There are different types of shaders, including vertex shaders and fragment shaders. Vertex shaders process the properties of 3D models, while fragment shaders determine the color and texture of each pixel. Together, they enable developers to create stunning graphics by manipulating how light interacts with objects in a scene.