Transposable elements, or transposons are major components of genomes. They are defined segments of DNA that have the ability to move or copy themselves into another location within and between genomes, even if those locations are non-homologous. Nowadays, a variety of transposons have been found in all three domains of life, and the number of identified elements is continuously growing due to the advent of high-throughput genome sequencing.

Transposases move DNA transposons to new locations, without the need for sequence homology between the transposon and the target site. Transposases contain a catalytic domain that mediates the breakage and joining of DNA. Together transposons and transposases form stable protein-DNA complexes called transpososomes.

Mu transposons have inherent capacity to insert into genome and simple requirements for the transposition reaction, which makes them ideal for a wide variety of applications.

DNA between the transposon ends can be designed to include useful features such as selectable markers, unique primer binding sites, reporter functions (such as the gene for β-galactosidase), plasmid origins of replication, and controlling elements (such as regulated promoters), and this makes transposons suitable for a number of different purposes.