In this day and age, you don't need a publishing house to publish a book. Self-publishing is possible and happening. There are several popular web serials (including, but not limited to, fan fiction). Do works have to be professionally published to count as literature, and if so, what counts as "professional"? 

Relevant comments:

1. [How would you distinguish fan-fiction from any other literature without professional publishing? Clarifying the defition a little might help answering the question (or resolve it altogether).](https://literature.meta.stackexchange.com/questions/142/is-fanfiction-on-topic#comment310_142)
2. [@muru Fanfic no. As brilliant as fic can be (which can easily eclipse formally published work), we're discussing formally published work. I would lean *more* towards "adaptations" and pastiches like *Clueless* and *Emma* because a novelization is, to me, a prose treatment of a script.](https://literature.stackexchange.com/questions/243/is-there-any-famous-literary-novel-that-was-based-on-a-movie#comment354_243) - I'm assuming that "formal" is equivalent to "professional" here.