You don’t need to turn off your iPhone often. If you’re not going to use it for a few hours, it’s not worth it (and the tiny savings in battery life) to turn it off.
But if you know you won’t be using your phone for a few days, or on a very long international flight, and you want to save every ounce of battery life, turning it off can be an effective option.
If you suspect a bug is making your phone unresponsive or sluggish, the first step to troubleshooting old IT standby should be: turn it off and on again.
To quickly turn off your iPhone hold either the volume button and the side button. Your phone will show a slider “slide to power off” at the top, along with sliders for SOS and Medical ID. Slide the Power off slider and your phone will turn off. If you have an iPhone 6s or earlier, short press the top or side button and the home button at the same time to make the sliders appear.
Force restart your iPhone
If you want to force restart an iPhone that is completely frozen and unresponsive, the procedure is a little different.
For all iPhones with Face ID and iPhone 8 or 2nd generation iPhone SE:
Quickly press and release the volume up button, then press and release the volume down button, then press and delay the side button. Keep holding it until the Apple logo appears and then release.
For iPhone 7:
Press and hold the volume down button and the side button at the same time. Keep holding until the Apple logo appears and then release.
For iPhone 6s or earlier:
Press and hold both the top/side button and the Home button. Keep holding until the screen goes blank and then the Apple logo appears (usually about 10 seconds or so). Then release both buttons.