James Clerk Maxwell ingeniously showed that electric and magnetic fields are both generated and altered by each other. This revolutionary discovery led to a novel and unique branch of physics, named electrodynamics. Electrodynamics successfully explains numerous physical phenomena, but ​is incapable of describing several empirical effects, such as the photo-electric and Compton effects, and also resulted in theultraviolet catastrophe. Max Planck, in an attempt to describe blackbody radiation, considered a discrete spectrum, i.e. an energy wavepacket, instead of a continuous spectrum for electromagnetic radiation. His theory, i.e. quantisation of energy, successfully described the radiation from a blackbody, and later on, was used by Albert Einstein to describe the photoelectric effect. This was a starting point for the development of one mankind’s best theories: Quantum Mechanics. Numerous ingenious scientists helped and contributed to both quantum formalism and quantum foundations since its inception. Here, in this course, we will focus on the quanta of light, i.e. photons, and its features, the way that they are generated, manipulated and detected. During the course, we will learn how the field quantisation leads to understanding unique effects such as Lamb shift, spontaneous emission, and spontaneous parametric down-conversion. Classical and non-classical light (Coherent, Thermal, Fock, and Squeezed) sources and their photon statistics will be discussed in detail. The action of different optical elements in the quantum regime, and seminal quantum optics experiments (e.g., Hanbury-Brown Twiss, EPR, Bell’s inequality, Hong-Ou-Mandel, induced coherence) will be reviewed during the course.