AU? OTP? Shipping? To those who don't frequent the online world of fandoms, these terms can seem like gibberish. But have no fear! I, fan-girl extraordinaire, am here to clarify!
1. Fandom
Fandom is the community around a certain person, movie, book, comic, etc.
Example: The Harry Potter fandom will never die.
2. Shipping
Shipping is a shortened form of relationship; it is used to declare your support for a particular romantic/sexual/platonic relationship.
Example: I totally ship Harry and Ginny!
3. OTP
OTP stands for one true pairing; it usually goes along with the term shipping. Your OTP is the relationship that you love/admire/obsess over above all others.
Example: Harry and Draco are my OTP.
4. Smut
Smut is usually used when talking about fan-fiction (a story written about a fandom not written by the original author). Smut refers to sexual activity in part of or the entire story.
Example: The later chapters of that fan-fiction is pure smut.
5. AU
AU is a very popular term/idea among fan-fiction writers; meaning "alternate universe", it allows writers can take their ideas to any level they want. (Like it the picture above, the artist has mixed The Avengers and Harry Potter)
Example: Did you see the new AU about Harry Potter and Suicide Squad?