More and more, I’m finding myself using mobile apps without ever opening them. I use apps like Moves and Dark Sky every day, but the app developers don’t know it.

Dark Sky sends me a push notification with a custom sound whenever it’s about to rain. I’ve become so accustomed to it that I no longer need to even take it out of my pocket when I receive an alert. The custom sound is enough.

Moves sends me a push notification every morning, telling me how many steps I took on the prior day. I don’t really need to open the app to learn more. A quick glance at the notification tells me what I need to know, and I am free to continue on with whatever I’m doing.

Moves and Dark Sky have no idea that they are providing value to me, since I typically do not take any action on the notification that is visible to the developer or even the OS.

The business impact is that companies are evaluated and funded on the basis of metrics like Daily Active Use, Monthly Active Use, Impressions, Visits. Notifications happen prior to all of these metrics.

The product impact is that if the goal is to deliver value in the notification itself, then these apps have no way of knowing whether or not their notifications are successful.

My hunch is that, for these two reasons, push notifications are an under-explored interface. Imagine an entire suite of apps with which you interact without ever opening. Imagine if app developers could send more data (images, videos) through push notifications, or even receive simple responses (“Yes” / “No”) from users without requiring users to launch the application itself.

Our phones and the apps within them are with us at all times — they are starting to feel more and more like extensions of the brain, augmenting its inputs with sensors that don’t come pre-installed in humans.

I’d love to see some forward progress in notification interfaces from the major mobile operating system. That’s the type of change that could unleash a massive wave of innovation in app development.