Russian formalist Vladimir Propp, in his book Morphology of the Folk Tale, described in rather abstract terms a set of recurring plot devices that he found in a certain genre of Russian folk tales. Not all of them are there and they don't all happen in the same order in the stories he studied, but they are a large part of how we recognize a text as a fairy tale; although sometimes you have to smush the tropes to make them fit right. This was probably one of the first critical trope-spottings.
Propp doesn't imply that the "functions" he found are universal in fiction (but some are very general), nor that they are an exhaustive description of fairy tales, nor that they are directly applicable to other traditions of fairy tales (but other European fairy tales are actually very similar to the ones Propp studied).
Propp's very popular work was important for two related structuralist ideas: that all fictional works have basically the same structure underneath, and that a story can be created by instantiating a sequence of abstract plot elements. Sound familiar?
The typical sequence of functions is:
- 0: The Initial Situation - The setup.
- 1: The Absentations - Someone leaves or dies. Usually a parent.
- 2: The Interdiction - A big rule is set up. Don't touch the spinning wheel. You can't go to the ball. You know the drill.
- 3: Violation - Someone breaks the big rule. This could be good or bad as seen by the examples above.
- 4: Reconnaissance - The villain spies on the hero or the hero learns about the villain.
- 5: Delivery - The searching party discovers information.
- 6: Trickery - Villain tricks hero.
- 7: Complicity - The hero is forced, tricked or influenced by magic to do something bad. There are bad consequences.
- 8: Villainy - Baddy McBadson does something really evil, normally stealing the Macguffin or kidnapping the princess.
- 9: Meditation - The goodies figure out a plan and get ready to set out on their quest.
- 10: Beginning counteraction - The heroes choose to fight back.
- 11: Departure - They... depart. Voluntarily or not.
- 12: First function of donor - The hero run into a donor or a magic dude. This character can be The Obi-Wan, a mysterious beggar or a "None Shall Pass" kind of character. They may have to pass a test. The hero may have to fight the donor. But on the bright side, the donor may have a magical object to help them on their quest.
- 13: Protagonist reaction - The hero outsmarts, outfights or finds a way around the donor's demands. He gets the Macguffin.
- 14: Acquisition of Magical Agent - The obi-wan type character. Can be the donor. This character helps the hero on his quest, sometimes willingly, sometimes not.
- 15: Transference - The hero is taken to a new place. Physically. Emotionally. Spiritually. Grammatically.
- 16: Struggle - Our hero (surprisingly) struggles.
- 17: Branding - Our hero for his efforts is marked out as a hero either with a token or with a mark on his body.
- 18: Victory - The hero beats the villain with his wits, his special abilities or his brawn.
- 19: Liquidation - The goodies all help the hero, and get what they were after.
- 20: The Return - Guess.
- 21: Pursuit - The heroes are chased by the villain, who is going all One-Winged Angel on them.
- 22: Rescue - The goodies run for it and escape by placing obstacles in the villain's path.
- 23: Unrecognised - The hero comes home and no one knows who he is because...
- 24: Unfounded Claims - Some Il Capitano-Zapp Brannigan-Gilderoy Lockhart character claims he saved the day.
- 25: Difficult Task - To prove he's the Hero the Hero must, well prove himself. It can be an ordeal of choice, a riddle or a test of strength.
- 26: Solution - The Hero chooses right/guesses right/wins the fight.
- 27: Recognition - Everyone realises that the hero is the hero through his special mark, the fact they got the right solution or through simple recognition.
- 28: Exposure - The false hero is shown up.
- 29: Transfiguration - The hero gets a makeover. Or at least new clothes or a palace.
- 30: Punishment - False Hero and Villain (and yes, they can be the same guy) get what's coming to them.
- 31: The Wedding - Usually the hero marries the princess or something like that, but the wedding can just be a general celebration from getting crowned to a party.
These are found in many folk tales, such as "Cinderella" and "Snow White", but also in more modern works like Labyrinth, The Lord of the Rings, Star Wars and Pan's Labyrinth. There are also elements of these devices found in even more ancient texts such as The Odyssey. See also The Hero's Journey.