* Lack of Cells: Living organisms are made up of cells, the basic building blocks of life. The sun is a giant ball of plasma, a superheated gas, and does not have any cellular structure.

* No Metabolism: Living things undergo metabolism, a set of chemical processes that sustain life. The sun doesn't metabolize anything. Its energy comes from nuclear fusion, a process entirely different from the chemical reactions in living organisms.

* No Growth or Reproduction: Living things grow and reproduce. The sun doesn't grow or reproduce in the way that living organisms do. While it does change over time, it's not a form of growth like in a living organism.

* No Response to Stimuli: Living things respond to their environment. The sun does not react to external stimuli in the way that living organisms do.

In summary, the sun is a massive, energetic star, but it does not possess the characteristics that define life.