What makes a novel "a classic"?

Calling a book a classic when it is first read it one's own personal judgement, but to me there is no doubt what a classic is. A classic is the kind of book that will be read for a very long time, years after its release. It would have to be a unique book, the first of its kind, to be given the title. It must obviously be high quality, but it doesn't have to be liked by everyone. Many classics today were criticized when they first came out. That means a book can't be called a classic until long after its release, to give it the chance to be seen in a different light. And it also must be a book kids in school are forced to read.