Caloric Theory is a historical scientific concept that proposed heat is a fluid called "caloric" that flows from hotter to cooler objects. This theory suggested that caloric was an invisible substance that could not be created or destroyed, only transferred. It was used to explain various phenomena related to heat and temperature. The theory was widely accepted in the 18th and early 19th centuries but was eventually replaced by the modern understanding of thermodynamics. Key figures in the development of caloric theory included scientists like Benjamin Thompson and Antoine Lavoisier, who contributed to the early ideas about heat and energy.