Neurotransmitters are chemical messengers in the nervous system responsible for transmitting signals between neurons or from neurons to other cells. When a neuron fires, it releases neurotransmitters into the synapse, the gap between neurons. These chemicals bind to receptor sites on neighboring neurons, influencing their activity by either stimulating or inhibiting the generation of action potentials. This process is essential for various bodily functions, from muscle movement to mood regulation. Examples of neurotransmitters include dopamine, serotonin, and acetylcholine.