A transposon, often referred to as a "jumping gene," is a segment of DNA that can move or "transpose" itself to different positions within the genome of a single cell. This movement can disrupt or modify the function of genes and can contribute to genetic diversity, evolution, and sometimes disease. Transposons are found in many organisms, including plants, animals, and bacteria, and they play a significant role in genomic rearrangements and the regulation of gene expression.