What Tc tells

Superconductivity has continued to be a fascinating phenomenon ever since its discovery in 1911. The magnitude of the transition temperature, T-c, provides valuable insight into the underlying physics. Here we provide select examples of the extensive research that has been done towards understanding T-c, and some cases where further investigation is called for. We believe that searching for new and enhanced T-c's remains a fertile frontier. (C) 2015 Elsevier B.V. All rights reserved.