Regression and Linear Models — The Workhorses You Should Understand First
Before neural networks, the two models that still quietly run more of the world's predictions than anything else are linear and logistic regression. They are simple enough to understand completely, fast enough to train on anything, and interpretable enough to explain to a regulator — and understanding them teaches the mechanics (fitting, loss, gradient descent) that every more complex model shares. This post builds both from scratch and shows why "just use a linear model" is often the right answer.
Linear and logistic regression still run more of the world's predictions than anything else — and they teach the universal loop (model, loss, gradient descent) that scales all the way to training an LLM. Fitting a line, the learning rate, and the sigmoid that becomes the softmax.