Brief overview of recent developments on negative phase-velocity mediums (alias left-handed materials)

This brief overview covers a rapidly occurring development in the area of microwave composite materials: isotropic dielectric-magnetic mediums wherein the phase velocity vector and the time-averaged Poynting vector are oppositely directed. Such materials have also been inappropriately designated as left-handed materials. Ramifications for aberration-free lenses, homogenization approaches, and complex mediums are also presented.