A.U.: Alternate universe - Something major differs from the universe the show is set in (aka the Jossverse). For instance, making sure that Angel didn't lose his soul when he and Buffy did the deed. Often, parts of the Jossverse will be used in the A.U. fic (either entire seasons are the same or the author will pick and choose from plotlines and even characters.)
Archive: A website that has many pieces of fanfiction from many authors. Often has a theme (i.e.-Willow/Angel or slash fic).
Archivist: Webmistress of an archive.
Archive fic: A piece of fic that is essentially an announcement about the archive. The characters in the fic are all aware of fans, the sites, etc. and act accordingly.
Badfic: A piece of fic that is purposely written so it is horrible. Can include one or all of the following: poor spelling, grammar, lack of punctuation, unbelievable plotlines, poor characterization.
Beta reader: Someone who reads your story for you, checking for spelling, grammar, punctuation, plot lines, and characterization. This occurs before you post your story to lists or an archive.
Buffyverse/Jossverse: The universe that the show we see every week occurs in, created by Joss Whedon.
Canon: Something that has occurred in the Jossverse. For instance, the fact that Angel lost his soul is canon. Anything that hasn't been explicitly stated or shown is not canon however.
Constructive Criticism: Criticism that is meant to give suggestions for improving a piece. Not meant to be mean or cruel, but meant to help the author.
Conventional Couple: A couple or pairing that has occurred in the Jossverse. Buffy/Angel, Willow/Oz are conventional couples.
Fanon: Something that has become accepted by a majority of authors/readers but has never been stated explicitly in an episode of "Buffy" or "Angel".
Feedback: Writing to an author after you have read their fanfic and telling them what you thought of it. This includes constructive criticism, but not flaming.
Femslash: A slash pairing where both participants are female. Hence the same FEMale slash. Willow/Tara are a femslash pairing.
Filk: Take a well-known song (any song). Change the words so they're about Buffy and Angel characters/plots. You now have a filk.
Flame: Feedback of an UNconstructive and cruel nature. Often insults both the author and his/her story, ideas, writing style. Does not provide suggestions and is always negative in tone.
Future piece/Futurefic: A story that is set sometime in the future.
Mary-Sue (Gary Stu): an original character based on the author him/herself. (For more info on Mary Sues, go to Writer's University.)
OC: Original character. A character made entirely up by the author of the story. Can be a Mary Sue.
Posting: To send your (hopefully beta read) fic to either a mailing list or an archive.
POV: Point Of View. Stories written in first person.
PWP: Porn Without Plot, Plot? What Plot?. Stories that are mostly smut with very little plot or dialogue.
Rating: If you noticed, all Buffy and Angel episodes had a little box in a corner stating what age group the episode was intended for. This is what you're doing for your fic so those who don't want to read NC-17 or R rated fics won't have to! (For different countries ratings please see Ratings.)
Slash: Stories where the relationship pairing consists of two people of the same sex. F/F slash is female/female (i.e. Willow/Tara) while M/M is male/male (Angel/Spike).
'Ship: short for relationship. It means what pairing the fic is about (Willow/Spike,
'Shipper: Someone who favors on 'ship over another.
Spoilers: Plotlines or information that tells people who haven't seen a particular episode all the
surprises and shockers that occur in it. I.E.-If you are writing about the Season 5 Finale, warn people what episode you're spoiling so those who haven't seen the finale yet won't have to be spoiled on the ending. It is important to remember that different countries start the new season at different times. In the U.S. it's September/October. However, in Australia it's February/March.
Songfic: A story that uses a song to help tell the plot or feelings of the characters.
UnConventional/UC couple: A relationship that hasn't (yet!) happened on the show.