Transposons are mobile genetic elements.
Autonomous transposons encode the functions needed for their own transposition. Ac is autonomous, while Ds requires Ac for mobilization . When a transposon inserts into an exon, gene function is normally reduced or eliminated. Practically, this means that if you can place Ds elements within a genome, then mobilize them using an Ac , you may induce a mutation in an interesting gene. Plainly, this works best if there isn't a huge background of other Ds elements in the genome.