Artificial intelligence (AI) is intelligence demonstrated by machines, unlike the natural intelligence displayed by humans and animals, which involves consciousness and emotionality. The distinction between the former and the latter categories is often revealed by the acronym chosen.
For people who want something older that's well documented: SDXL
For people who want the new fancy thing: Flux (vram hungry with 16fp dev, but you can go 8p or you can use the schnell variant, which just means "fast")
For people who want the faster image generation: SDXL lightning.
For tools, people are split on using either python/huggingface, the automatic1111 webui or comfy UI, which is my personal favourite.
The hottest model now is flux, and the community is gravitating toward it after the failure of stable diffusion 3.
Tooling around it is still nascent and it is very demanding (12GB+ VRAM GPU highly recommended) so you could also start with Stable Diffusion XL, fairly mature at this point.