Passenger DNA refers to genetic material that does not play a significant role in an organism's development or survival. Synonyms for passenger DNA include non-coding DNA, junk DNA, or repetitive DNA. Non-coding DNA is genetic material that does not encode proteins, while junk DNA refers to regions of the genome with no known function. Repetitive DNA is DNA with repetitive sequences that do not contribute to an organism's genetic makeup. Passenger DNA can accumulate mutations over time and can be used to study the evolutionary history of a species. With the advancement of sequencing technologies, scientists can analyze passenger DNA to gain insights into genetic diversity and the role of non-coding regions in genome regulation.