Even though people seem to put out a teaser website for anything these days, let’s step back and think about why one would need a teaser.
After all, putting one together takes time and energy, and you could argue that the effort would be better spent on the product itself.

1. But a teaser can go a long way to ensuring a successful launch.
2. Raising awareness of your product long before it ships makes sense: people are more likely to interact with your app if they’re somewhat familiar with it, so letting them hear about it as soon (and as much) as possible helps.
3. Ideally, you would create a climate of anticipation, and make people look forward to the release date.
4. People love to know in advance about the next big thing, and you can use it to your advantage.