The commercial has to sell itself first
A short teaser at the start of a longer ad is a miniature pitch: it gives viewers a reason to wait for the rest. Instead of beginning with setup, the ad may flash its most surprising image, a joke in progress, or a question whose answer comes later. The teaser is not necessarily a separate ad; it is a compressed preview of the commercial that follows.
A hook buys a few more seconds
Viewers can skip, scroll past, or simply look away, so an ad has little time to earn attention. A rapid opening can create a small information gap: the audience sees enough to wonder what happens, but not enough to resolve the moment. That curiosity can carry them into the slower explanation, story, or product reveal.
The opening also has to make sense at high speed. If it is only a jumble of images, viewers may not understand why they should stay. The teaser must signal the ad’s tone or central idea while withholding just enough to make the next beat feel worthwhile.
The preview creates a creative tradeoff
Giving away the strongest moment too early can leave the full commercial feeling repetitive. Hold back too much, and the teaser offers no reward for staying. Advertisers therefore have to make the opening work twice: as a tiny piece of entertainment on its own and as a doorway into a longer message.
That is why some commercials begin like trailers. Before an ad can persuade someone about a product, it may first have to persuade them not to leave.
