An action potential is an electrical signal that travels along neurons, caused by the movement of ions across the neuron's membrane.
Depolarization: This is when positive ions rush into a neuron, making it less negatively charged and triggering an action potential.
Repolarization: This is when positive ions are pumped out of a neuron after an action potential, returning it to its resting state.
Refractory period: This is a brief period after an action potential during which a neuron can't fire another one.