Backpropagation in Neural Networks
1. Imagine a Student Taking a Test
- Input: The student sees a question (like the input layer of a neural network).
- Thinking Process: They go through steps in their brain to reach an answer (like the hidden layers doing math with weights and biases).
- Answer: The student writes the answer (like the network producing an output).
- Feedback: The teacher marks it wrong and tells the correct answer.
- Learning: The student realizes where they made a mistake, goes back through their thought process, and adjusts how they think next time.
Neural Network Version of That
- Forward Pass:
- Inputs go through the network.
- It produces an output (a prediction).
- Compare with the Real Answer:
- Check how wrong the prediction was (this is called loss or error).
- Backpropagation (the key idea):
- The network works backwards from the error.
- It calculates how much each neuron and weight contributed to the mistake.
- Update Weights:
- The network adjusts the weights a little using this info.
- This makes the future prediction slightly better.
This repeats every time with new examples → and over time the network gets smarter.
Simple Analogy:
It’s like adjusting our aim after every dart throw by figuring out how far off you were and why — so our next throw lands closer to the bullseye.
Backpropagation in Neural Networks – Backpropagation example with Simple Python