Process dynamics is an academic field and methodological approach focused on the quantitative description and analysis of how systems evolve over time. It investigates the transient and steady-state behavior of processes, examining the relationships between inputs, internal states, and outputs under dynamic conditions. This field is characterized by the development and application of mathematical models, often differential equations, to understand system response, predict future states, and inform the design, control, and optimization of dynamic systems across diverse scientific and engineering domains.