The synapse is the link between two neurons, one being the presynaptic neuron and the other being the postsynaptic neuron. The presynaptic neuron launches neurotransmitters from the axon terminal of the presynaptic cell across the synapse (the space between the neurons) to the receptors of the postsynaptic cell. Some neurotransmitters don't make it, and are then sucked back into the presynaptic cell to try again.
