The Hertzsprung-Russell diagram, also known as the H-R diagram, is a graph showing the relationship between stars' absolute magnitudes/luminosities vs. their temperatures/spectral types. While the HR diagram does not map out the physical location of stars, it does plot stars together to measure and compare brightness and temperatures. Towards the top right of the diagram are the giants and supergiants. At the bottom left are the white dwarfs. From the top left to bottom right of the diagram, a line is formed called the Main Sequence. This is where stars spend the majority of their lives.