High-mass stars play a crucial role in shaping the evolution of galaxies through their intense radiation, powerful stellar winds, and eventual supernova explosions. However, their formation process remains poorly understood compared to that of low-mass stars, as they form deeply embedded within dense molecular clouds located at large distances. This chapter provides an overview of the current understanding of high-mass star formation from both theoretical and observational perspectives. It outlines the main proposed formation scenarios, emphasizes the importance of studying the physical and dynamical properties of dense cores where high-mass stars are born, and introduces infrared dark clouds as plausible birthplaces of high-mass stars. Finally, it highlights the key open questions that the subsequent chapters aim to address.