Complex phase diagrams are generic feature of quantum materials that display high temperature superconductivity. In addition to d-wave superconductivity (or other unconventional states), these phase diagrams typically include various forms of charge-ordered phases, including charge-density-waves and/or spin-density waves, and electronic nematic states. In most cases these phases have critical temperatures which are comparable in magnitude to that of the superconducting state. In these systems the high temperature state is not a 'good metal' with well-defined quasiparticles but a so-called “strange metal” in which the quasiparticles are ill-defined. These states typically arise from doping a strongly correlated state known as a Mott insulator. With my collaborators we have identified these behaviors as a problem with “Intertwined Orders”. A Pair-density wave is a type of superconducting state which embodies the physics of intertwined orders. In this colloquium I will discuss the phenomenology of intertwined orders and the quantum materials that are known to display these behaviors.