Final answer:
The part of the chart that details what each wedge represents is called the key, which is essential for understanding the data distribution within a chart such as a pie chart.
Step-by-step explanation:
The part of the chart that indicates what each wedge represents is known as the key or legend. When looking at a chart, such as a pie chart, the key is typically a small box or section of the chart that explains the color or pattern associated with each wedge or section. It helps the viewer understand which data series each color or pattern corresponds to, thereby making sense of the data presented in the chart.