The Sun is our nearest star at a distance about eight light minutes. It is not much compared to the four-light-year distance of the second nearest star, Proxima Centauri. The Sun was born about five billion years ago and will continue to shine for another five billion years before it will turn into a red giant. Its energy is created in a fusion reaction of hydrogen atoms into helium.

An overview of the Sun's parts.

The three  major interior zones are the core (the innermost part of the Sun where energy is generated by nuclear reactions), the radiative zone (where energy travels outward by radiation through about 70% of the Sun), and the convection zone (in which convection currents circulate the Sun's energy to the surface).

The Sun converts 600 million tons of hydrogen into 596 million tons of helium every second .. the rest goes into energy.