The document discusses client-side deep learning and introduces MPSCNN, a library that allows running convolutional neural networks on iOS devices using Metal Performance Shaders. MPSCNN can import trained models from frameworks like TensorFlow and run them to perform tasks like object detection on images at 60 times per second. Client-side deep learning could enable new mobile applications for areas like self-driving cars, AI assistants, and cancer detection by taking advantage of on-device processing power.