Using a selection of key experiments performed over the past 30 years or so, The Quantum Divide presents a discussion of the strikingly counter-intuitive phenomena of the quantum world that defy explanation in terms of everyday "common sense" reasoning, and it provides the corresponding quantum mechanical explanations with a very elementary use of associated formalism. Most, but certainly not all, of the experiments it describes are optical experiments involving a very small number of photons (particles of light). The book begins with experiments on the wave-particle duality of electrons, proceed to experiments on the particle nature of light and single photon interference, delayed choice experiments and interaction-free detection, then goes on to experiments involving the interference of two photons, quantum entanglement and Bell's Theorem, quantum teleportation, large-scale quantum effects and the divide between the classical and quantum worlds, addressing the question as to whether or not there is such a divide.