A choropleth is a visualization in the form of a map. The areas of this type of plot are shaded or patterned according to the value associated with them. It basically shows the geographical characteristics of an area mentioned in our dataset. These maps are very popular due to the ease of readability.
Why do you need it?
A choropleth map helps us to see our irregular disturbed data visually in the form of region, countries, states, etc. on their respective map, thus they are easy to understand and effective in reading and finding out the desired conclusions. If there is a count of people present in an area, then these maps are not useful. If there is a count of people per square mile, then this ratio is appropriate for these maps.
What kind of data you can visualize with it?
The dataset that has regional-data is good for choropleth maps. Assume you have a data of income tax rates by countries, then this map is the spell to use as a visualization. Some examples of these types of the dataset are a map showing the percentage increase in home value by Australians, a map showing a number of births per 1 lakh for a certain year reported by a country.