Abdel Ibrahim, writing for WatchAware, on the Apple Watch Taptic engine:

With the Watch, Apple has introduced its Taptic engine, whose goal is to help alert you to various items through various taps on your wrist. These taps are not audible and can’t even be detected by the person next to you. The idea is clearly to take advantage of your body’s ability to “feel,” and Apple is putting this to good use by taking advantage of the new paradigm as it benefits a variety of tasks.

One example, as explained by Apple, is the Watch’s ability to tap you when you need to make a turn along some GPS-plotted course. The fact that you can be tapped and told in silence “Hey, get ready to take a right turn!” is a far different — and by my expectations, a far better — experience than having some semi-robotic voice tell you that it’s time to hang a quick right.

That’s an interesting use case, though I am not sure a tap alone would be enough to add value to the Apple Watch as direction-giver. With a single tap, for example, there’s no way to distinguish between left and right [Dave: apparently there is a way – cool!], or left and get in your right lane. Siri and Apple Maps excel at direction-giving, even without access to the screen.

That said, I can certainly see a number of cases where a tap at the right time could make all the difference. Anytime where you can hear yourself saying “and…now” to get the timing of something just right is a candidate for the Apple Watch. Of course, a tap to tell you when the pasta is done is an easy example.

But if you are doing something that requires delicate and precise timing, a tap at the right moment could be a tremendous help. Purely to help illustrate the point, consider serving a tennis ball. You throw the ball up in the air, then go through a series of precise timed movements to make sure your racket arrives at the right moment to meet the ball. I’m not suggesting that the Apple Watch is the right solution here, just making the point that a tap at the right moment can help you develop muscle memory when precise timing is required.