Stable Diffusion is the open-source AI image generation model that democratized AI art. Released by Stability AI in 2022, it made high-quality AI image generation accessible to anyone with a consumer GPU — no API fees, no content restrictions, full local control. Unlike proprietary tools like Midjourney or DALL-E, Stable Diffusion runs locally on consumer hardware. Users with an NVIDIA GPU can generate unlimited images at no cost, in complete privacy, with full control over every parameter. This openness sparked an explosion of community innovation: thousands of fine-tuned models, LoRA adapters, and extensions now exist for every conceivable style and subject. Stable Diffusion is the engine underlying most major AI image platforms and tools. Automatic1111 (AUTOMATIC1111/stable-diffusion-webui) is the most popular community interface, offering controlnet for pose and composition control, inpainting, outpainting, and hundreds of extensions. ComfyUI provides a node-based workflow approach for advanced users. Stability AI has released multiple versions: SD 1.5, SDXL, SD 3, and Stable Cascade — each improving quality, prompt adherence, and resolution. SDXL Turbo and Lightning versions generate images in 1-4 steps instead of 20-50, enabling near-real-time generation. For developers and businesses, Stability AI provides API access to all models. Stable Diffusion's open license (with some commercial restrictions) and Stability AI's API make it the foundation layer of the AI image generation ecosystem.