Most of the time you'll want your iOS devices on and ready to go with a press of the Sleep/Wake (On/Off) or Home button. And most of the time, it'll work just fine at that press. But your device is essentially a small computer, and computers slow down sometimes: As such, you may want to power off your iPhone or iPad for a period of time, or you may want to restart it — or even reset it — to get it working properly.
How to power off or restart your iPhone or iPad
Press and hold down the On/Off button on the right side (iPhone 6 or later) or top (all other iPhones, iPods, and iPads) of your device for 3 seconds.
Swipe the slide to power off confirmation slider to the right.
How to force your iPhone or iPad to restart
Press and hold down the On/Off button on the right side (iPhone 6 or later) or top (all other iPhones, iPods, and iPads) of your device.
While continuing to hold the On/Off button, press and hold theHome button on the front of your iPhone, iPod touch, or iPad.
Hold both buttons as the screen turns off, and keep holding them until the screen turns back on and displays the Apple logo.
Silver, gold, and rose devices will show a white screen with black Apple logo. Space gray devices will show a black screen with white Apple logo.