The Machine Learning “Advent Calendar” Day 18: Neural Network Classifier in Excel

Here is a **short, clear excerpt**, written in your style and suitable for Medium or Towards Data Science: — Neural networks are often presented as black boxes, hidden behind high-level libraries and abstract concepts. In this article, we build a neural network classifier from scratch using Excel, with every computation written explicitly. Starting from forward propagation and ending with backpropagation, we show how the model is defined as a simple mathematical function and how its parameters are learned using gradient descent. No shortcuts, no hidden steps, just the mechanics that make neural networks work.