What does a pie chart effectively display?

A pie chart is an effective tool for displaying the proportions of a whole category. It visually represents data as slices of a circular "pie," where each slice corresponds to a part of the total. This is particularly useful when you want to show how different segments contribute to an overall total, facilitating an immediate understanding of the relative size of each segment.

For example, if you were displaying the market share of various companies within an industry, a pie chart would allow viewers to quickly grasp which company holds the largest share and how the others compare proportionately. This emphasis on part-to-whole relationships makes pie charts particularly effective in situations where the goal is to communicate the distribution of data categories relative to the entire set.

Other options are less suited to this type of representation; for instance, a pie chart does not effectively display total counts, relationships between multiple variables, or chronological data, which are better represented through other types of charts like bar graphs or line charts.