The Cumulative Distribution Function (CDF) is a statistical tool that describes the probability that a random variable will take a value less than or equal to a specific number. It provides a complete picture of the distribution of the variable by accumulating probabilities from the lowest value up to the chosen point. The CDF is useful in various fields, including statistics, finance, and engineering. The CDF is defined for both discrete and continuous random variables. For discrete variables, it sums the probabilities of all outcomes up to a certain value, while for continuous variables, it involves integrating the probability density function (PDF). The CDF always ranges from 0 to 1, making it easy to interpret probabilities.