Giving solid proof that there is take up and customer interest in your product.
Who is buying already? How many customers do you have? Is there growth in the business - with users, revenue?
If you already have success and paying customers, then don't be afraid to tell your audience about it clearly in the pitch.
(And what if you don't have traction yet? You'll see what to do in the next chapter!)
Exercise: Brainstorm your Traction.
See how successful startups have pitched their traction and progress.