Everyone talks about co-packaged optics as the future of AI networking, but most explanations only cover one piece of the system. What's missing is a holistic understanding of how all the pieces fit together. CPO isn't just a purely photonic problem, but a complex system-level co-design challenge involving optics, mixed signal circuits, fabrication, and packaging. I wrote an all-in-one technical overview that connects these disciplines and explains the major engineering challenges involved. This article covers: - Advanced packaging and FAU challenges - Semiconductor fabrication and manufacturing - Light manipulation and photonic devices - Light generation and popular laser architectures - EIC architectures for the driver and trans-impedance amplifier.