An article in the New York Times today discusses how the iPhone and other smartphones now have a way to make the device unusable if it’s stolen — a so-called “kill switch.”

In Apple’s iPhone and iPad, it’s called Activation Lock. It prevents other people from using your phone, turning off Find My iPhone, or wiping your phone.

But you need to set it up ahead of time! Don’t wait until it’s too late.

Here’s how to set up Activation Lock on your iPhone or iPad.

1. You must be running iOS 7.
2. Enable Find My iPhone: On your device, go to Settings > iCloud, sign in with your Apple ID, and turn on Find My iPhone.

And once you’ve set up Activation Lock, here’s what to do if your iPhone or iPad is lost or stolen:

1. Sign in to icloud.com/find from any computer.
2. Put the device in “Lost Mode” to set a 4-digit passcode and display a custom message on the screen.
3. Optionally, from here you can also remotely erase your phone.

For more info go to Apple’s support page on Activation Lock.

Photo by Jim Crossley from Flickr Creative Commons.