Here's why:

* Our Perspective: The Sun appears brightest to us because it's the closest star to Earth.

* Other Stars: There are many stars far brighter than the Sun, but they are much further away, making them appear dimmer in our sky.

* Brightness vs. Luminosity: Brightness is how bright a star appears from Earth, while luminosity is a star's actual power output. The Sun is a medium-sized star with a medium luminosity.

So, the Sun is the brightest star for us, but not the brightest star in the universe.