Points in Mosaic Charts occupy the entire data bounds. The area of each point corresponds to its contribution to a total of all data points (like in Pie Chart), not just relative to its own category (like in Percent Stacked Column Chart). Both X and Y axes in the Mosaic Chart type are always categorical/ordinal.
A Mosaic Chart usually works well for displaying statistical data with more than two parameters in addition to regular X and Y values (n-way tables).
Mosaic Chart illustrating the importance of five different skills - statistics, programming, mathematics and operations research, machine learning and big data, and business - for each of the four data jobs: Data Businessperson, Data Creative, Data Developer, and Data Researcher.