A cumulative distribution function (CDF) is a fundamental concept in statistics that describes the probability that a random variable takes on a value less than or equal to a specific point. It provides a comprehensive view of how values are distributed across a range, allowing for easier comparisons and visualizations than traditional probability mass functions (PMFs). CDFs are particularly useful in understanding the behavior of data, as they accumulate probabilities, making it easier to analyze trends and patterns. By plotting a CDF, one can quickly assess the distribution characteristics of a dataset, such as its center, spread, and potential outliers.