Do you remember when They Might Be Giants famously covered a 1959 children's song called 'Why Does The Sun Shine?' It begins like this:
The sun is a mass of incandescent gas
A gigantic nuclear furnace
Where hydrogen is built into helium
At a temperature of millions of degrees
I thought I'd start the morning with a bit more detail 50 years after the original... At temperatures over 13 million K, the fusion of hydrogen atoms into helium produces much of the sun's power. Every second, ~ 4.4 Mt of matter is converted to energy by way of thermonuclear reactions in this star's core, and (following Einstein's mass-energy equation) that's a rate about 30 trillion times higher than our yearly use of all primary electricity and fuels on planet Earth. (And no, I haven't come up with a new tune yet...)