What great invention do you think is most important?

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I was watching National Geographic today and they were talking about how the machine gun and barbed wire totally revolutionized trench warfare in WWI, so that got me thinking about all the inventions in the last few hundred years and which one I would consider to be most important. Not just weapons and stuff, even daily things that we use can count. I personally think electricity is probably pretty major, since all of today's technology relies on electricity and stuff. If we didn't realize how to harness all that energy, you probably wouldn't be sitting in front of your computer reading this right now lol. So which invention do you think is most important in daily life?