what makes a novel a classic?

i don't exactly know what the criteria of a classic novel is. does it have to be a so-called "good" novel? does it have to be a bestseller? i don't know. but what i do know about classic novels is that modern day books and movies are based off of them. such as romeo and juliet. almost every love story has to do with them. and wuthering heights sounds similar to it. i know there's death that corresponds with the love that catherine and heathcliff have with one another. 

a classic novel has a very interesting plot and story line, and we are required to read them in school. it's very unique and is respected with admiration. and to be completely honest, hopefully the book Twilight doesn't become a classic. yes, i've read all of the books and i love them. but they are not classic novel material. one of the books has a quote based off of wuthering heights! Twilight... yeah right. no matter what screaming 12-16 year old girls say... it should not be a classic novel.

classic novels are something that i definitely have to read because i want to be an english major in college. i'm exposed to some and they all have different story lines. whether it be pride and prejudice, romeo and juliet, or the adventures of tom sawyer-- they all create different worlds to engulf my interest.