The Boltzmann Factor is a mathematical expression that describes the probability of a system being in a particular energy state at thermal equilibrium. It is given by the formula e^-E/kT , where E is the energy of the state, k is the Boltzmann constant, and T is the absolute temperature in Kelvin. This factor helps explain how particles distribute themselves among various energy levels in a system. In statistical mechanics, the Boltzmann Factor plays a crucial role in understanding the behavior of systems at the microscopic level. It shows that higher energy states are less likely to be occupied than lower energy states, especially at lower temperatures. This concept is fundamental in fields like thermodynamics and quantum mechanics, influencing how we understand phenomena such as chemical reactions and phase transitions.