Three-color matching in pie charts refers to the selection of three colors that are harmonious and visually appealing when used to represent different segments of a pie chart. The choice of colors should consider color theory, contrast, and the specific context of the data being presented. It is essential to ensure that the colors chosen are distinguishable from each other and do not cause visual fatigue or confusion. Common color schemes for pie charts include monochromatic, complementary, and analogous schemes.