Nucleation is a process in which new phases or crystals form from a supersaturated solution or vapor. It involves the formation of small clusters of atoms or molecules that serve as a starting point for the growth of larger crystals or phases. Nucleation is a fundamental step in various physical and chemical processes, such as crystal formation, cloud formation, and phase transitions. Research in nucleation aims to understand the mechanisms and kinetics of nucleation, as well as to develop strategies to control and manipulate nucleation processes for various applications, such as in materials science, pharmaceuticals, and atmospheric science.