specialized junctions at which a neuron communicates with a target cell; presynaptic terminals release a chemical transmitter stored in synaptic vesicles which diffuses across a narrow synaptic cleft and activates receptors on the postsynaptic membrane of the target cell; the target may be a dendrite, cell body, or axon of another neuron, or a specialized region of a muscle or secretory cell; do not confuse with the immunological synapse, see cross reference for that concept.