Why is the sun the brightest star?

Answer 1

The Sun isn't the brightest star, actually it's considered quite dim in relation to other stars.
It appears brightest as it is closer to earth. There are other stars, some bigger or smaller, brighter or duller, in the vastness of the universe outside our rather small collection of planets orbiting our sun.

Answer 2

The sun is the brightest star in our sky because it is relatively close to Earth compared to other stars. Its brightness is also due to its size and the amount of energy it releases through nuclear fusion in its core.

Answer 3

It appears the brightest because it is comparatively close to us. It is a rather average star.