  Electromagnetically induced transparency and Autler-Townes splitting are two
distinct yet related effects. These phenomena are relevant to quantum
technologies, including quantum memory, quantum switching, and quantum
transduction. Here, the similarities and differences between these phenomena
along historical and conceptual lines are discussed and their realizations on
various physical platforms including atomic gases, superconducting circuits,
and optomechanics are elaborated. In particular, the author clarifies two
approaches to assessing which phenomenon is observed based on a black-box
approach of modeling the output, given a particular input vs analyzing the
underpinning physics. Furthermore, the author highlights the ability to effect
a continuous transition between the two seemingly disparate phenomena.
