"The Hertzsprung–Russell diagram, abbreviated as H–R diagram, HR diagram or HRD, is a scatter plot of stars showing the relationship between the stars' absolute magnitudes or luminosities versus their stellar classifications or effective temperatures. More simply, it plots each star on a graph plotting the star's brightness against its temperature (color)."
- Wikipedia
The H-R diagram is plotted using the Hipparcos Catalogue of 118,218 stars and their measurements.
Based on the H-R diagram blog post by Eduardo Martín Calleja.