Here's why:

* Stellar Classification: Stars are classified based on their mass, temperature, and luminosity. The most common classification system is the spectral classification, using letters from O to M (O being the hottest and most massive, and M being the coolest and least massive).

* Our Sun's Classification: Our Sun is classified as a G-type star. G-type stars are considered intermediate-mass stars, falling between the massive O and B stars, and the low-mass K and M stars.

* Low-Mass vs. Intermediate-Mass: While our Sun is technically an intermediate-mass star, it's more accurate to categorize it as low-mass due to its relatively small size and mass compared to the most massive stars.

To summarize:

* High-mass stars: O and B stars (very hot and bright)

* Intermediate-mass stars: A, F, and G stars (like our Sun)

* Low-mass stars: K and M stars (smaller and cooler than our Sun)