Somatic genetics is the field of study dedicated to investigating the genetic and epigenetic characteristics and alterations that occur within the somatic (non-germline) cells of an organism throughout its lifespan. It focuses on acquired genetic variations, such as mutations, chromosomal rearrangements, and epigenetic modifications, which arise after fertilization and are not typically transmitted to offspring, playing a critical role in development, aging, disease pathogenesis (particularly cancer), and individual phenotypic diversity.