The article is mostly a short and simplified explanation of the H-R diagram and it honestly doesn’t do much to help with understanding it but it does have nice pictures and a good quality image of the H-R diagram.
Hertzsprung-Russell diagrams are used to categorize all the stars out there in the big black. They are organized on a spectrum that shows their luminosity and their temperature. This diagram is invaluable in studying stars. It helps to organize the jumble of stars that are all around us and that are ever expanding. We spent time in class explaining this diagram and we talked about ‘oh be a fine gal kiss me’ in order to remember the temperature spectrum.