Delta Tc (ΔTc) is a derived asphalt binder property that has been gaining attention for the last decade. It has become a topic of focus to both researchers in the asphalt binder technical community and user agencies seeking physical property parameters that will improve hot mix asphalt pavement performance. It is generally accepted that ΔTc targets cracking behavior that is affected by asphalt binder durability related to aging of the binder in an asphalt mixture. More specifically, ΔTc provides insight into the relaxation properties of a binder that can contribute to non-load related cracking or other age-related embrittlement distresses in an asphalt pavement. It is a calculated value using the results of the bending beam rheometer test determined on laboratory-aged asphalt samples or samples recovered from pavements. At the time this document was developed (mid-2019), ten user agencies have or soon will implement ΔTc as part of their purchase specification, with two more expecting to do so in the near future. In addition, several national level research projects are actively considering ΔTc as part of their studies. In fact, ΔTc was first hypothesized via a research project led by the Asphalt Institute.