Synapse is a junction between the axon terminal of one neuron and the dendrite of next neuron. It is separated by a small gap known as synaptic cleft. 

A synapse is formed by the membranes of a pre-synaptic neuron and a post-synaptic neuron which may or may not be separated by a gap called synaptic cleft. Chemicals involved in the transmission of impulses at chemical synapses are called neurotransmitters.

There are two types of synapses.

(a) Electrical synapse

(b) Chemical synapse

In electrical synapses, the pre and post synaptic neurons lie in close proximity to each other. Hence, the impulse can move directly from one neuron to another across the synapse. This represents a faster method of impulse transmission.

In chemical synapses, the pre and post synaptic neurons are not in close proximity. They are separated by a synaptic cleft. The transmission of nerve impulses is carried out by chemicals such as neurotransmitters.