As someone in AI, which concept blew your mind away when you first learnt about it?

For me? It was GradCAM was a gamechanger at selling computer vision initiatives internally to the non-technical stakeholders.

The gradCAM function computes the importance map by taking the derivative of the reduction layer output for a given class with respect to a convolutional feature map. If you have a 5 layered convolutional neural network, then you can use this against any layer and check the class activation map.

The best explanation to give is: "Regions in Red are the areas of the image that the neural network is looking at to make a decision"

Well to be honest, regions in red represent the class activations arising from that region but, it would be too much for normie business guys.