Periodization serves as a powerful tool for organizing data, discerning developmental patterns, and forecasting future trends. This chapter explores a variety of approaches, including the derivation of mathematical relationships, intellectual synthesis, and the comparison of diverse frameworks. While the volume presents various periodizations, their complementary nature underscores the importance of integrating multiple approaches to better understand complexity across scales. Key themes include addressing gaps in terminology and complexity metrics, comparing cosmic and terrestrial evolutionary trajectories, and leveraging periodization to predict future developments. These insights converge toward a holistic understanding of complexity across cosmic, biological, and societal dimensions, shedding light on humanity’s and the universe’s evolutionary paths. Two primary stages for understanding complexity in Big History are the development of physical and complex adaptive systems. The first stage tracks the progression from the Big Bang through stellar and planetary formation to the emergence of life, characterized by decreasing potential energies and increasing organizational complexity. The second focuses on life’s evolution, marked by hyperbolic growth across biological, human, and technological phases, with stages accelerating geometrically. Key insights include the cascading interplay between evolutionary layers, the dual dynamics of horizontal and vertical evolution, and the non-deterministic nature of complexity development. Identified patterns, such as geometric accelerations and scaling behaviors, provide a foundation for forecasting future trends and understanding rapid systemic transformations. Challenges in unifying theories of complexity and evolution are discussed through proposing integrated frameworks that incorporate energy flow, information theory, and evolutionary timelines. Methodological considerations focus on interdisciplinary research, abstractness levels, and evaluating existing periodizations against complexity metrics, evolutionary mechanisms, and temporal scopes. The chapter concludes by outlining future directions for advancing Big History periodization and announcing a forthcoming volume that will explore complexity across cosmic, biological, and societal phases, aiming to deepen understanding and foster interdisciplinary dialogue within Big History studies.
