The electric potential that is generated in a postsynaptic neuron during the transmission of a nerve impulse (see synapse). It is caused by depolarization of the postsynaptic membrane when a neurotransmitter (such as acetylcholine), released from the presynaptic membrane, binds to the postsynaptic membrane. This will induce an action potential in the receiving neuron if the EPSP is large enough. See facilitation. Compare inhibitory postsynaptic potential.