What is the most important invention in 21st century? 5/20

I talked about it with my English teacher. It is very difficult question, I thought. First of all, smartphone came to my mind. Smartphone has changed our life. We can access many kinds of information anytime and anywhere. Additionally, we can talk with people, buy something, listen to music, play games, take some lessons, watch some videos, and so on. It is innovative. 

However, I wondered whether there are more important thing than smartphone. My English teacher thinks 3-D printer is. 3D printer also brings  us many kinds of benefits. 3D printer will enable us to make other beneficial inventions. We will be able to develop the way to treat patients of crucial disease. An article says that 3D printing will change the manufacturing flow and enable everyone to make what they want to create by themselves. People and companies will be able to make things without special tools. It might enable everyone to be inventors. 

From the internet to the iPhone, here are the 20 most important inventions of the last 30 years

I found another article. It picked up the 20 most important inventions. I thought smartphone is so, but the internet is also very important invention. Many people create something new so our lives are more convenient. Artificial intelligence would be created in the future. I think too much convenience will be harmful for human, but I’m also looking forward to new inventions.