I think a lot about power buttons these days. With modern devices — especially smartphones — we don’t really use them as power buttons, because our phones are never really off. But that’s a double-edged sword, because while they don’t actually “power” on our phones, we press them more than ever: my iPhone X’s “power” button probably gets pressed dozens of times every day now. 

And it’s that iPhone power button that I specifically want to talk about: the one on Apple’s most recent Face ID iPhones. When Apple killed the home button with the iPhone X, it also killed the hardware trigger for Siri — you can’t press and hold a home button that doesn’t exist, after all. 

Power buttons are a subtle reflection of trends in modern technology. When smartphones first came about, nearly every phone had a power button on top of the device. As screen sizes grew, and that top edge got farther and farther away from the reasonable reach of most thumbs, the power button migrated to the side. When screens grew larger and home buttons went extinct, the power button got built-in fingerprint sensors. And Apple is no different: the iPhone power button experiences the same trends.  

So when Apple killed the home button, it changed two things about the power button, too. First, the power button on the iPhone X is twice as big as prior models, so it’s always easy to press it. And it now activates Siri when held down, instead of offering the shutdown prompt (the other main function of the iPhone home button). Both of these shifts make sense, logically. iPhones were getting bigger, and making the button easier to press is a natural extension of that. And as the last major button left on the phone, having the power button trigger Siri was essentially the only option (short of adding some kind of dedicated Siri button, anyway).

But the side effect is that the power button on current iPhones can’t actually do the one thing it’s supposed to: actually turn the phone on and off (a separate command that requires holding it and the volume up button together is needed to actually shut the phone off entirely).

It was a frustrating change at first, but the difference is a positive one, I think. I use Siri for simple tasks like setting alarms and adding reminders to return Amazon packages far more than I did to turn off my phone. And putting that function in the power button — which I nearly always have a thumb on when holding my phone, even more so than the home button — makes it even more accessible. Plus, the bigger button is just more enjoyable to press, especially on brand-new devices when the click is still nice and crisp.

Some Android phones are following this trend, too: the Note 10’s power button doesn’t shut off the phone, and OnePlus phones can be customized to launch Assistant with a short press. 

Even as we’re starting to see phones that eschew buttons entirely, some kind of hardware to turn on a device is still needed. And as smartphones continue to get increasingly innovative and fresh designs, it’s a safe bet that the power button will continue to change along with them.