Resource :: ControlNet
ControlNet acts as a sophisticated add-on for Stable Diffusion. It works by taking additional images or sketches and using them as guides to steer the image generation process.
Link to ControlNet for A1111 (GitHub)
Link to ControlNet (GitHub)
How to install/use
Everything you need to know is available on the GitHub page.
Stable Diffusion Art provides an extended and well written guide.
You can also ask Gemini.