Synapse

The synapse is the entire junction between neurons, including the pre-synaptic neuron's axon terminal, the synaptic cleft, and the dendrite of the post-synaptic neuron, across which communications flow, usually in the form of neurotransmitter molecules secreted by the pre-synaptic neuron (on its axon terminal) that travel a short distance across the synaptic cleft (this is the actual space between the neurons - the space between the axon terminal of one neuron and the dendrite of the other) to the post-synaptic neuron.

Once at the post-synaptic neuron, some of the neurotransmitters will attach themselves (bind) to some receptors. It is important to know that the neurotransmitters and receptors work like a lock and key; that is, they both have certain shapes and only specific neurotransmitters can fit into certain receptors.