A heatmap is a data visualization tool that employs color-coding to represent different values within a matrix or a dataset. It is often used to show the level of activity, intensity, or performance in various areas of a given space or scenario. For instance, in website analytics, a heatmap can illustrate where users click the most, indicating areas of high engagement. In a geographical context, it might show population density or the prevalence of a particular phenomenon, such as crime rates or disease outbreaks, with colors ranging from cool to warm to indicate low to high values, respectively. Heatmaps are also common in scientific research to display complex data, such as gene expression levels in different samples. The visual nature of a heatmap makes it easier for viewers to quickly grasp patterns, trends, and outliers within the data, making it a valuable tool for analysis and decision-making across various fields.