Three inflection points
Deep learning's modern history is short and sharp. 2012 — AlexNet: a CNN trained on two GPUs cuts the ImageNet top-5 error roughly in half overnight. The community, until then sceptical of neural nets, pivots within a year. 2014–2017 — the architecture rush: VGG, GoogLeNet, ResNet, attention mechanisms, sequence-to-sequence models, batch normalization, Adam. The toolbox we still use today gets built. 2017 — Transformer: Attention Is All You Need proposes a recurrence-free architecture that scales horizontally on GPUs/TPUs. By 2018 BERT and GPT had eaten NLP; by 2020 it had eaten vision (ViT) and speech.
The ingredients that made it possible
None of this was algorithmic genius alone. Three things had to align: data (ImageNet, the open web), compute (GPUs going from a graphics oddity to general-purpose tensor engines), and differentiable software (Theano, Caffe, then PyTorch and TensorFlow). Researchers in 1995 had similar ideas; they did not have any of the three.
What the arc tells you about the next ten years
Each inflection looks obvious in retrospect and shocking in the moment. The arc has not stopped — foundation models, multi-modal training, and reasoning-oriented post-training are the current frontier. The pattern is the same: better representations, more data, more compute, more ergonomic software. Building intuition about which ingredient is binding for your problem is more useful than memorizing the dates.