68. PCA: Shrinking Data Without Losing Information

You have 100 features. Most of them are correlated. Training is slow. Visualization is impossible. KNN is useless (curse of dimensionality). PCA is the tool that handles this. It takes your 100 features and finds 10 new features that capture 95% of the original information. Training gets faster, visualization becomes possible, and your models often get better too. It's one of those techniques you'll use constantly once you understand it. What You'll Learn Here What PCA actually does in plain ter