The physics of heavy nuclei demands an understanding of large amplitude shape changes. Nuclear fission in particular has a prominent role as a source of energy, and as a terminator of r-rocess nucleosynthesis. The quest to extend the chart of nuclides to superheavy elements is sharply constrained by the inverse of fission, the heavy-ion fusion reaction, as well as by the depletion of superheavy progenitors by fission itself. Even after 70+ years since its discovery, nuclear fission remains an active field of experimental research and continues to pose formidable challenges to theory. It is a crucial source of mid-mass isotopes to access the part of the nuclear chart at high neutron excess asymmetry.