who do you think is the greatest inventor or what do you think is the greatest invention ever. it could be locally or international

THis is my greatest
The Toilet and Modern Plumbing. Go ahead. Laugh. Then try to imagine New York City without toilets. You can't. The ability to remove sewage from and bring clean water into places of dense human habitation makes the modern city possible. Without it, we'd still have cities, but not like the ones we know. A high-rise building would be impossible, really, without toilets and plumbing. Remove apartment buildings, office towers, and dense downtown cores from your picture of the world and you have to change the whole rest of your picture too, because the implications keep rippling.