What makes a novel "a classic"? Discuss.

In school I have read many books that are novels and are read every year because they are considered classic. I do not agree with some of the books that we have read are classic, but I understand why they would be. Even though this is somewhat of a true story, when we read Malcolm X I absolutely hated reading it and thought that it was a horrible book. On the other hand, I understand how Malcolm had helped to change the lives of the black people for the better. An example of a novel that I love is Harry Potter. Harry Potter, even though we do not live in a life with magic, is an excellent book that many people are addicted to. I think for a book to become classic, the book has to be interesting and has to relate to what the reader thinks.