Willis Lamb once said that a license should be required for the use of the word “photon”, and he would not hand out very many written licenses. So far Quantum Electrodynamics (QED) has been a complete theory of electromagnetic (EM) fields that in essence has explained every aspect of light-matter interactions. Yet there are numerous rich phenomena that arise in light-matter interactions at low energy scales that were previous unknown and are actively being studied by the quantum optics community. In addition, quantum optics has been playing a leading role in the testing of the axioms of quantum mechanics, while also exploring ways to build new technologies exploiting quantum phenomena. In this talk, I will give a historical review of the development of the idea of photons and elucidate why there was some resistance in the quantum optics community to the notion of a quantized EM field, some even claiming that QED was unnecessary to explain the low energy EM field. I will also discuss photon statistics and photon interference, drawing examples from some historical experiments that played a pivotal role in clearing some of the doubts that people had about the nature of the EM field. If time permits, I will give a brief introduction to my work in a related field.