Circadian biology is the academic field dedicated to the study of biological rhythms that exhibit an endogenous, self-sustaining oscillation with a period of approximately 24 hours. This research investigates the molecular, cellular, and systemic mechanisms governing these circadian clocks, their entrainment by environmental signals such as light and temperature, and their critical role in regulating diverse physiological processes, behavioral patterns, and overall homeostasis and adaptation across a wide range of organisms.