The sun is the star at the centre of solar system and its mass accounts for about 99.86% of mass of the entire solar system.
Currently it is in the middle of its main sequence stage, after which it will probably expand and consume inner planets possibly including earth.
Hydrogen and Helium account for almost entire mass of the sun, and remaining. 1.69% are heavier elements.
There are some other interesting facts which we are unaware of about the sun and they are: sun undergoes a cycle every 40 years where the suns magnetic poles flip and this cyclic process happens in two phases.
During this phenomenon there are storms formed on the surface of the sun releasing a huge amount of radiation energy into the universe.