A hook is a promise of an emotional payoff, compressed to three or four words. At thumbnail size, you are not explaining the video — you are making a bet with the viewer: click and feel something.
The formats that consistently go viral are patterns, not magic. "I QUIT ___" (stakes). "STOP DOING ___" (correction). "$X IN Y DAYS" (numbers + deadline). "THE ___ SECRET" (withheld knowledge). "24 HOURS OF ___" (challenge). "DON'T WATCH ___" (fear). Fill the blank with your topic and you have a working hook in seconds.
Brevity is the rule that overrides everything. Count your words: over ten and you have a title, not a hook. The video title field carries the details — the thumbnail only has to trigger the click.
Numbers beat words. "$10K" reads instantly; "ten thousand dollars" is a paragraph. Dates, ranks, percentages — any digit is a CTR magnet, and it should be the biggest element on your canvas.
Test two hooks, not vibes. Write your favorite and your second choice, export both with the A/B test card (Pro), post both videos, keep the winner after 48 hours. Most creators are wrong about which hook wins — data beats taste every time. The hook ideas tool in the editor generates all these formats from your topic with one click.