What scientific discovery or technological invention do you choose as being important?

When people are asked about the most important discoveries or inventions made in the last two hundred years, they usually mention something very obvious, like the computer or the cell phone But there are thousands of other discoveries or inventions that have had a huge impact on how we live today. What scientific discovery or technological invention from the last 200 years- other than computers and cellphones- would you choose as being important? Why?

I mean we're so used to science and technology that we are not even aware of all the things we use in our daily lives. I would probably choose space satellites. This technology happened in the last hundred years and it has become important for so many things. Just think about navigation, or telecommunications, or even the military.

I am thinking about medical progress. Like, for example, when scientists discovered things about healthy nutrition. I am thinking of identifying all the vitamins we need to stay healthy. I am not sure exactly when the vitamin discoveries happened, but I know they are very important. Our health is much better than it was 200 years ago.