Did the Chinese Discover America?

Since we were kids we have heard that Christopher Columbus was the main character of the discovery of America. In primary school, high school or university we learned the same. Many researches has been done in order to confirm if that information is or not accurate. This one that is mentioned in the book is really interesting. I had never heard about the chinese as the discoverers of America. I don't have too much to say about it because I'm not good at history but  as far as I can say, there are too many doubts around the world about who was the real discoverer of America. This is a very controversial topic.