The sun is the brightest star we see because it is much closer to us than any other star.
The brightest star would be the Sun. See related question.
The Sun
because it is the closest to the earth
sun is the brightest star in the galaxy
Our Sun is the closest star to Earth, therefore, the brightest.
Sirius is the brightest star in the night sky, but the brightest overall is the sun.
The brightest star as seen from Earth is the sun. The brightest star in the night sky is Sirius.
Our sun is not the brightest star in the universe. It only appears brighter because it is much close than any other star. The brightest star as it appears in the sky is Sirius.
The Sun
Sirius
As the question specifies brightness, the brightest star in the Universe is our Sun - because it is the closest star to us. The most luminous star is another question: See related question.
yes yes the sun is a star but not the biggest or brightest