The article reviews the development of shot noise in mesoscopic conductors, focusing on its theoretical and experimental aspects. Shot noise, a consequence of charge quantization, provides unique information about the system that cannot be obtained from conductance measurements alone. The review covers various methods for analyzing shot noise, including scattering theory, Langevin and Boltzmann-Langevin approaches, and classical methods. It discusses the sensitivity of shot noise to electron-electron interactions and highlights the differences between thermal noise and shot noise. The authors present a comprehensive list of references and rederive key results using different methods to ensure clarity and completeness. The review also addresses the limitations of current approaches and identifies unsolved problems, offering insights into future research directions. The article concludes with a summary of the field's current state and a list of important unsolved problems.The article reviews the development of shot noise in mesoscopic conductors, focusing on its theoretical and experimental aspects. Shot noise, a consequence of charge quantization, provides unique information about the system that cannot be obtained from conductance measurements alone. The review covers various methods for analyzing shot noise, including scattering theory, Langevin and Boltzmann-Langevin approaches, and classical methods. It discusses the sensitivity of shot noise to electron-electron interactions and highlights the differences between thermal noise and shot noise. The authors present a comprehensive list of references and rederive key results using different methods to ensure clarity and completeness. The review also addresses the limitations of current approaches and identifies unsolved problems, offering insights into future research directions. The article concludes with a summary of the field's current state and a list of important unsolved problems.