The Sun is the star of our solar system. Around it gravitate the Earth, seven more planets, three dwarf planets, asteroids, meteoroids, comets and dust. Despite the large amount of objects orbiting around it, the Sun accounts for over 99% of the total mass of the solar system. Without the energy it irradiates, life on Earth would be impossible.
The Sun is a third-generation star of the G2V class. The G means its surface temperature is average (5770 K), which gives it a white colour (it only appears yellow because of the atmosphere scattering), and the 2 refers to its luminosity, brighter than 85% of the stars of the galaxy (most of which being red dwarfs); the V part indicates its a main sequence star, generating energy by nuclear fusion of hydrogen nuclei into helium and is in a state of hydrostatic balance, neither contracting nor expanding over time.