Synapses are the points of communication between neurons. They can be either chemical or electrical. In a chemical synapse, an action potential triggers the release of neurotransmitters from synaptic vesicles in the presynaptic neuron. These neurotransmitters then cross the synaptic cleft and bind to receptors on the postsynaptic neuron, initiating a response. Electrical synapses involve direct electrical connections through gap junctions, allowing for the rapid transfer of electrical signals.