Copyright was created so that everyone could use their creativity to come up with new ideas. Websites, books, music, and television are a few examples of things that are copyrighted. This means that it is illegal for those things to be copied the exact same. Copying and sharing other people's work requires permission.
Fair Use tells us what we are allowed to use of other peoples' work. It creates rules so that we can use other peoples' ideas without getting in trouble.
I have attached an article that explains copyright and a website that includes a helpful video.
Creativitiy, Copyright, and Fair Use