A familiar idea

You have already seen the core idea of this module, just in a different form.

A transistor is a switch: on or off. That binary logic was the foundation of the first three modules.

A biological neuron is similar in one way: it receives signals and may fire only when those signals are strong enough. But it is different in an important respect. Neurons can be more or less active — not just fully on or fully off.

That flexibility is part of what makes neural systems so powerful. A switch can only say yes or no. A neuron can help represent something closer to how much.