Categorical analysis is the foundation of data visualization. It is the first and most frequent type of data visualization that data analysts use. To visualize a small data set containing multiple categorical (or qualitative) variables, you can create either a bar plot, a balloon plot or a mosaic plot.
For a large multivariate categorical data, you need specialized statistical techniques dedicated to categorical data analysis, such as simple and multiple correspondence analysis. These methods make it possible to analyze and visualize the association (i.e. correlation) between a large number of qualitative variables.