A choropleth map visualizes geographical data by coloring regions based on a quantitative variable. It transforms numeric values into color gradients, helping users quickly see spatial patterns.
For example, a choropleth map might show unemployment rates by region across a country, with darker shades representing higher rates. This allows policymakers or analysts to identify areas that need intervention.
Choropleth maps are widely used in economics, politics, and epidemiology. They are best for normalized data (like rates or percentages), as raw counts can mislead due to population size differences.