Overfitting occurs when a model captures training data too closely, including its noise, instead of learning patterns that generalize to unseen data. In a compression view, an overfit model resembles a giant lookup table: it stores examples rather than capturing their regularities. section 8.2.1
Limited data made early neural networks especially prone to overfitting. AlexNet showed that a highly overparameterized network could still generalize when data augmentation and dropout helped mitigate the problem. section 2.0 section 2.5.3
AlexNet and the complexity trade-off
AlexNet trained 60 million parameters on 1.2 million images. Random crops, reflections, and color changes simulated variation in the training data; together with dropout, they helped the model generalize. A model that is too complex may memorize noise, while one that is too simple—like a straight line fitted to a complex curve—misses important structure. section 2.5.3 section 8.2.1























