What do American people celebrate?

You are going to visit some websites and watch some videos to find out.

http://www.ivillage.com/thanksgiving-childrens-thanksgiving-story/6-a-144239
http://kids.nationalgeographic.com/kids/stories/history/first-thanksgiving/
http://www.scholastic.com/scholastic_thanksgiving/

Videos
The Story of Thansgiving
The story of Thanksginving Basically