Shader Model 3.0 is a graphics programming interface introduced by Microsoft as part of the DirectX 9.0c API. It allows developers to create more complex and realistic visual effects in video games and applications by providing advanced features like dynamic branching and increased instruction limits. This enables more detailed textures and lighting effects, enhancing the overall visual quality. With Shader Model 3.0, developers can write shaders that execute more efficiently on compatible hardware, improving performance. It supports a wider range of graphics cards, making it accessible for both high-end and mid-range systems. This model has played a significant role in the evolution of real-time graphics rendering.