YOLO stands for You Only Look Once. It’s an object detection model used in deep learning use cases, of which there are mainly 2 main families:
The idea of one-stage detection (also referred to as one-shot detection) is that you only look at the image once.
Stating that it was simply a bit better than YOLOv2, but not much changed.
YOLOv4 was then recently introduced as the “Optimal Speed and Accuracy of Object Detection”.