Natural hydrogen (white hydrogen) is found in diverse geological environments (Fig. 2.1), originating from distinct geological processes that drive its generation, migration, and entrapment (Zgonnik in Earth-Science Reviews 203, 2020). Natural hydrogen accumulations have been identified in diverse geological settings, including igneous rocks, kimberlites, ore deposits, Precambrian basement units, salt structures, sedimentary and metamorphic sequences, ultramafic rocks, volcanic systems, and coal basins, each characterized by distinct geologic conditions that favor hydrogen generation, migration, or retention (Prinzhofer et al. in International Journal of Hydrogen Energy 43:19,315–19,326, 2018;Maiga in Scientific reports 13:11,876–11,876, 2023;). The following sections provide a comprehensive analysis of these formation types, emphasizing their H2 generating mechanisms, critical influencing factors, and illustrative case studies where applicable.