How is information passed across a synapse?

A synapse is a junction between neurons. For neurons to communicate signals to each other, it is vital that information can cross the synapse when appropriate.

The neuron before the synapse (the presynaptic neuron) communicates with the neuron after the synapse (the postsynaptic neuron) through chemical signals. The presynaptic neuron releases neurotransmitters which diffuse across the gap between neurons (the synaptic cleft) to act on receptors on the postsynaptic neuron, and to stimulate the initiation of an electrical impulse in the postsynaptic neuron, effectively 'passing on' the impulse.