Heat Map Chart, or Heatmap is a two-dimensional visual representation of data, where values are encoded in colors, delivering a convenient, insightful view of information.
Essentially, this chart type is a data table with rows and columns denoting different sets of categories. Each cell in the table can contain a numerical or logical value that determines the cell color based on a given color palette.
All these features make Heat Maps a handy data visualization tool for comparing categories, using color to emphasize relationships between data values that would be much harder to understand in a simple table with raw numbers.
To make a Heat Map easier to grasp, it is possible to make its cells display the corresponding values, such as numbers for numerical data or symbols (dots, ticks, etc.) for logical (Boolean) values.