Booking Through Fanfiction

What do you think of fanfiction? In general—do you think it’s a fun thing or a trespass on an author/producer’s world? And of course, obviously specific authors have very firm and very differing opinions about this, yet it’s getting more popular and more mainstream all the time. Do you ever read or write it yourself?

I am not much into fanfiction. I don't read it and writing it out of question. Maybe if someone offered me a book better than the original, I might consider reading it!