A transposable element is often called a transposon. It is a sequence of DNA that can move to new positions in the genome of a single cell. The press sometimes call them jumping genes, but it is not correct to call them 'genes'.
Transposons were first found by Barbara McClintock while working on maize in the 1930s to 1950s. She discovered transposition in maize, but it took years before her work was understood. She received a Nobel Prize for her work in 1983.