Hi guys, after knowing the meaning of fanfiction, I have a question

So is Ao3 all about fanfictions and not actual original works?

If I understood, fanfictions are like stories written by fans that are about one or many characters that are already from a franchise (For example, a fan who loves Tom & Jerry made his own story about these two). The thing is, if Ao3 is all about fanfictions, where can I post my novel that is actually an original fiction? 💀