Without it, there are no stars, including our own sun, and there wouldn’t be us talking about it.
It is used in particularly destructive bombs.
At a tiny scale, it can be used to produce neutrons, eg, a Farnsworth Fusor.
At a large scale, we have yet to figure out how to make controlled fusion work in a way that runs for a long time and generates collectible power we can use to feed the process. This has remained elusively 20 years out from the current state of affairs for 50 years.
If it was made to work, then it would probably be a good source of clean energy that would be safer than many of the non-renewable alternatives.
I don’t expect to live to see it happen.
