High brightness muon beams hold great promise for future high energy physics facilities. Use of this heavy lepton in a Muon Collider would allow efficient acceleration and storage in recirculating structures and excellent energy resolution with the full center-of-mass energy available for physics reach. However, with a lifetime of 2.2 microseconds at rest, muons are difficult to produce with large phase space density and all beam manipulations must be made quickly which rules out most beam cooling techniques. One of the main technical challenges for a Muon Collider is cooling the muon beam down to a size that would fit through an affordable accelerator acceptance and produce large luminosity for physics. Ionization cooling is a technique to lower the emittance of a muon beam using energy absorbers to shrink the momentum vector and acceleration along the beam axis to restore the longitudinal component. The Muon Ionization Cooling Experiment (MICE) has demonstrated muon cooling in a short section of cooling channel using liquid hydrogen and lithium hydride energy absorbers, showing the increase in phase space density at the beam core with excellent agreement between simulated and observed performance. This brings us closer to a new class of future machines based on muon beams.