**Preface to "New Spin on Metal-Insulator Transitions"**

Electrons in solids behave differently compared to free electrons in vacuum, which is incorporated in the effective mass m\* of electronic quasiparticles. In extreme cases, their mutual interactions can even result in qualitatively different behavior such as the localization of conduction electrons upon a metal–insulator transition (MIT). Near such electronic instabilities, unconventional superconductivity, non-Fermi-liquid transport, exotic magnetism, and other interesting electronic phases are stabilized in correlated electron systems. This Special Issue provides a view into the ongoing research endeavors investigating emergent phenomena around MITs.

> **Andrej Pustogow** *Editor*
