This paper will focus on the theoretical and experimental study of light-matter interaction in photonic structures. We will therefore start by describing quantum optical models of optical cavities and waveguides. Then we will describe the basic physics behind light matter interactions, and provide a theoretical analysis of the phenomena that result from it. Finally, we will describe single-photon sources, their characterization and introduce solid-state platforms that can be employed for their implementation. Throughout this paper, we have tried to provide a sound and complete description of the theoretical underpinnings of the seminal experiments in quantum optics. Detailed derivations of some of the results employed in the main text have been provided in the appendices.