The primary function of a GPU (Graphics Processing Unit) in gaming and computer graphics is to render images and perform complex calculations needed for visual effects. GPUs are designed to handle many parallel processes, which makes them particularly efficient for rendering high-quality graphics in real-time applications such as video games. They accelerate tasks like texture mapping, lighting calculations, and shading, significantly enhancing visual fidelity. By offloading these tasks from the CPU, GPUs enable smoother gameplay and improved overall performance in graphics-intensive applications.