HEATMAP
Heat map
A heat map is a graphical representation of data where the individual values contained in a matrix are represented as colors. Fractal maps and tree maps both often use a similar system of color-coding to represent the values taken by a variable in a hierarchy. The term is also used to mean its thematic application as a choropleth map. The term "Heatmap" was originally coined and trademarked by software designer Cormac Kinney in 1991, to describe a 2D display depicting real time financial market information.The above text is a snippet from Wikipedia: Heat map
and as such is available under the Creative Commons Attribution/Share-Alike License.