What inventions in the history of manking do you regard as most important?

It is no doubt that mankind history is full of important and significant events and inventions. To my mind, one of the most important inventions is penicillin. A scientist named Alexander Fleming was doing research at Hospital in London and he was looking for something to fight bacterial infections. Use of penicillin did not begin at once. Howard Florey and Ernst Chain isolated the active ingredient and developed a powdery form of the medicine. So they were able to make enough penicillin to establish it as a value drug. The world now had a valuable treatment that would save the lives of millions. Penicillin today is a very important prescription drug. It is very effective against fungi, parasites and bacteria.