The tie-in novel is literature involving the characters of a TV
series, film or other work and usually written by some author
you've never heard of. Pretty much anything can have a tie-in
novel. They're often compared to authorized {{fanfic}}, in that
they're usually not part of the main continuity, do things that
would never be considered in the original, and are widely
variant in quality. If a series is exceptionally popular, the
tie-novels may have their own micro-continuity. If it's mega-
popular, expect them to occupy their own ExpandedUniverse.
Expect tie-in novels by the same author to refer to events in
their other novels.  These novels are usually written in a very
conservative style. You're unlikely to encounter one written in
the style of Margaret Atwood or Marcel Proust.  These can be
{{novelization}}s of episodes or "untelevised adventures".  See
{{Novelization}} for a main continuity story retold in book
form. For the reverse--going from a book to the big screen--see
TheFilmOfTheBook. For a simil