Design is a process to determine optimal combinations of ingredients and processing parameters for desired performances of a product. The ingredients for materials design are their chemical compositions, and processing parameters are temperature, pressure/stress, and electric/magnetic fields with the outcomes being the phases and their morphologies, i.e., microstructures, which dictate the performances of materials. In the history of human civilization, those optimal combinations were obtained through extended periods of trial-and-error experimentations such as the tin content in bronze and blacksmith procedures. Human knowledge has been accumulated through apprenticeships, books, journals, and the latest digitization as the core of the 4th industry revolution. The digitization of knowledge on phases and their properties in last century can be broadly categorized as bottom up from quantum mechanics and top down from CALPHAD modeling. In this presentation, author’s experiences and perspectives on these two approaches will be discussed (https://doi.org/10.1016/j.actamat.2020.08.008, https://doi.org/10.1080/21663831.2022.2054668).