A cumulative frequency graph, also known as an ogive, is a graph used in statistics to show the cumulative frequency distribution of a set of data. The cumulative frequency at each point on the graph represents the total number of observations that fall below that point. It is a line graph that displays the cumulative frequencies of the data set at different intervals. The ogive is useful for determining the median and quartiles of a data set, and for visually displaying the shape of the distribution.