Final answer:
The primary mode of communication between two neurons is through chemical synapses, where neurotransmitter chemicals are released from the presynaptic cell and bind to receptors on the postsynaptic cell.
Step-by-step explanation:
The primary mode of communication between two neurons is through chemical synapses. At a chemical synapse, neurotransmitter chemicals are released from the presynaptic cell into the synaptic cleft between cells. These chemicals travel across the cleft to the postsynaptic cell and bind to receptors embedded in its membrane, transmitting signals between the neurons.