I hear the term "plot hook" a lot, but I've never understood exactly what it means. I thought it was a method for introducing the player characters to an adventure, but the term doesn't seem to be used that way. Take, for example, this list of plot hooks on Reddit. I see in this list things that seem to serve completely different purposes, but are all called plot hooks. For example:
- A way the player's are introduced to a conflict, while leaving the exact nature of the conflict open for the DM to fill in.
A farmer passing by tells of a nearby villages that have been struck with plague.
- A description of a status quo, without any mention of how to involve the players.
A shipwreck on a nearby coast is swarming with orc raiders.
- A description of a scene that is just about to play itself out.
2 paladins have met in a field, each with a second, and a herald, to fight a duel of honor.
- A story element the DM could introduce into the players' lives that would encourage stories emerging naturally during normal play.
The party finds a fully charged (100 uses) Wand of Wonder. It cannot be thrown away, and compels the user to point the wand and shout the command word ("SHICKETYSHAK!") every time the owner enters combat or the boundaries of a village, town or city. Once 100 charges have been expended, the Wand teleports 100 miles away, and fully recharges.
Anecdotally, I've also had at least one DM use the term "plot hook" to describe a plot device that moved a character to the place where the adventure was taking place in a coherent way.
Player: I have my character's backstory, but I'm not sure why they would end up on the same island as the rest of the party.
DM: Don't worry about it. I've got a plot hook for you for when we start playing.
DM: [At the beginning of the game] You receive a letter from an old colleague of yours. In it, he invites you to a weekend at his estate. You were never very close with him, but you always knew he came from wealth, and his estate sounds very luxurious. What do you do?
With so many various things that serve such wildly different purposes, I'm left confused as to what it is that actually constitutes a plot hook. Some of the things on this list sound like the start of adventures before the players enter, some of them sound like ways to get the players to enter any potential adventure, and some of them sound like things for the DM to do to the players, independent of actually tying an adventure to that action. All useful things for a DM, to be sure, but with wildly different motivations behind them.
So, what gives? What is the actual definition of a plot hook? For bonus points, are the items on this list actually plot hooks, or just various things that might inspire a DM?