The H-R diagram consists of several distinct regions:
- Main Sequence: This is a continuous band where stars spend the majority of their lifetimes. Here, stars are in a stable phase, fusing hydrogen into helium in their cores. The position of a star on the main sequence correlates with its mass; more massive stars are hotter and more luminous.
- Red Giants and Supergiants: Located in the upper right of the diagram, these stars are in a late stage of their evolution. They have exhausted the hydrogen in their cores and expanded, cooling in the process.
- White Dwarfs: Found in the lower left, these are the remnants of stars that have shed their outer layers. They are very hot but have low luminosity due to their small size.
