The core user experience is not a set of features; in fact, it is the job users hire the product for. Uber’s core user experience is to get a taxi easily at any time. The countdown, displaying when exactly the taxi will arrive, is a suitable feature that expands this experience. But Uber’s product works regardless of this feature. The countdown, on the other hand, cannot live without the product (the certainty to get a taxi easily at any time). There is a one-way interrelationship between feature and product: Features don’t work without the product. This is why designers should think in products first.