When you’re not using iPhone, press the Sleep/Wake button to lock iPhone. Locking iPhone puts the display to sleep, saves the battery, and prevents anything from happening if you touch the screen. You can still get phone calls, FaceTime calls, text messages, alarms, and notifications. You can also listen to music and adjust the volume.

On iPhone 6, iPhone 6 Plus, iPhone 6s, and iPhone 6s Plus, the Sleep/Wake button is on the right side:

The upper portion of iPhone with a close-up of the Sleep/Wake button

On iPhone SE and iPhone 5s and earlier, the Sleep/Wake button is on the top edge:

A close-up showing the Sleep/Wake button

iPhone locks automatically if you don’t touch the screen for a minute or so. To adjust the timing, go to Settings > General > Auto-Lock.

Turn iPhone on. Press and hold the Sleep/Wake button until the Apple logo appears.

Unlock iPhone. Press either the Sleep/Wake or Home button, then drag the slider.

Turn iPhone off. Press and hold the Sleep/Wake button until the slider appears, then drag the slider.

For additional security, you can require a passcode to unlock iPhone. Go to Settings > Touch ID & Passcode (iPhone models with Touch ID) or Settings > Passcode (other models)