Why is studying the 20th Century important ?

I think that 20th century history is very important to study so we can learn our backgrounds and heritage, and how things came to be today. It is important to know not only for 20th century history, but all history. History can teach us mistakes that we have made in the past, and we can try and avoid making the same mistakes again. Many of the inventions we use today were created in the 20th century.