This lecture covers the quantization of photonic states in various dimensions, focusing on quantum wells, wires, and boxes. The instructor begins by discussing the possible energy states for quantization in the z-direction, followed by calculations for the y and z directions, and finally for all three dimensions. The concept of density of states is introduced, explaining how it varies in 1D, 2D, and 3D systems. The instructor elaborates on the conditions for polarization in different configurations, emphasizing the significance of boundary conditions in determining the allowed states. The lecture also addresses the implications of these quantization principles for photons, comparing them to electrons and discussing the statistical mechanics involved. The instructor concludes by highlighting the importance of understanding these concepts for applications in quantum science and technology, particularly in the context of photonic devices and materials.