H II regions are areas of space where the dominant source of ionizing radiation is hydrogen (denoted as H) that is ionized (hence, H II). These regions are typically found surrounding hot, young stars and are characterized by their glowing emission of hydrogen alpha light. H II regions play a crucial role in the formation and evolution of galaxies, as they are often associated with star formation activity. Studying H II regions can provide insights into the physical conditions, chemical composition, and dynamics of the interstellar medium.