Stars are really burning balls of gas even though they don't really appear to be from earth.
The stars that we see in the sky are huge spheres of hot gas which mostly consists of hydrogen gas which generate light and heat through a process that is called nuclear fusion.
The nuclear fusion happens in the stars core, where hydrogen atoms combine and form helium.
When the hydrogen atoms combine to form helium in the stars core it releases energy in the process.
As a result the stars glow and the stars appear in the sky and shine through the night sky.
Stars are mostly hydrogen with some helium and a trace amount of heavier elements.
Nuclear fusion is the energy source of stars in which hydrogen atoms fuse into helium and release energy.
A star's immense gravity pulls the gas inwards and creates the pressure that is required for the fusion to occur.
And the light that you see from stars is the energy that is being produced by the fusion escaping from it's surface.
Stars that are fusing hydrogen to helium in it's core is called a main sequence star.
Main sequence stars make up around 90 percent of the universe's stellar population.
And they range in size, color and luminosity, from a 10th to 200 times the mass of the Sun and live for millions to even billions of years.