Here's why:

* Mass: The Sun's mass is about 1.989 × 10^30 kg, which places it in the category of medium-mass stars. Stars are classified by their mass, and the Sun falls somewhere between the very low-mass red dwarfs and the high-mass blue giants.

* Stage: The Sun is currently in the main sequence stage of its life. This is the longest stage of a star's life, where it fuses hydrogen into helium in its core. Our Sun has been in this stage for about 4.5 billion years and is expected to continue for another 5 billion years.

Let me know if you'd like to learn more about the different types of stars or the stages of stellar evolution!