A Probability Mass Function (PMF) is a fundamental concept in probability theory that describes the distribution of discrete random variables. It assigns a probability to each possible outcome of a discrete event, ensuring that the sum of all probabilities equals one. For instance, when rolling a fair six-sided die, the PMF indicates that each face (1 through 6) has an equal probability of 1/6. PMFs are essential for understanding the likelihood of specific outcomes in various applications, such as games of chance, statistical analysis, and decision-making processes. They provide a clear framework for quantifying uncertainty in discrete scenarios.