Hook
The opening seconds whose only job is to make staying feel more interesting than leaving.
The hook is the beginning of a piece (commonly the first three to five seconds on short-form, the first fifteen to thirty on long-form), and its job is narrow: give the viewer a reason to still be there a moment from now.
Structurally, most hooks that work do one of a small number of things. They pose a question the viewer wants answered. They show the end state and promise to explain it. They contradict something the viewer believes. They present an image strange enough to demand explanation. Almost none of them begin by introducing themselves.
A hook is not a slogan and it is not the title. It's the first structural move of the piece, and it makes a promise the rest has to keep. A hook that oversells produces exactly the retention cliff it was meant to prevent, just twenty seconds later.
Where this comes up
A hook isn't a slogan. It's the first structural move of a piece, and it makes a promise the rest has to keep. The five that work and why.
Your thumbnail will be judged at the size of a postage stamp, moving, next to twenty others. Design for that, and test it properly.