If your Mac's been stolen or you've left it somewhere there is some pretty nifty technology that can help you find it again. The only proviso it that you need to have set it up first. 

If you have enabled Find My Mac on your Mac, you’ll be able to track down your lost computer. (See also: How to trace a stolen MacBook: use Find My Mac to find stolen MacBook.)

How can I set up Find My Mac? 

Open the iCloud preference pane in System Preferences. If you’re aren’t already logged in to iCloud sign in. Now all you have to do is make sure you’ve selected the Find My Mac checkbox. You need to make sure that Location Services are enabled and you need to make sure that it is set to wake for Wi-Fi network access. To ensure that your Mac can be woken remotely, click the Power Adapter tab and select Wake for Wi-Fi network access. To allow Location Services, Open Security & Privacy, choose the Privacy tab, and select Enable Location Services. 

After you turn on Find My Mac, you’re set – you don’t need to do anything else unless your Mac falls into wayward hands.

How can I find my Mac using Find My Mac? 

As long as you have set it up, should the worse happen, you can use Find My Mac to location your computer. You can use the iPhone app called Find My iPhone (it will locate your Mac and iPad too), or your can log into iCloud via the web. 

To locate your Mac using the Find My iPhone iOS app launch the app on your iPhone or iPad. If you haven’t got the app you can download it for free from the App Store. Log on to the app using your iCloud log in and password and the app will locate your registered devices, as long as they are online. It won’t locate them if they are turned off. 

Similarly you can log onto iCloud on the web (www.icloud.com) and go into the Find My iPhone service there.

Find My iPhone will locate your device and it will show it on the map, where you can zoom in and out, and switch between Map, Satellite, and Hybrid views. You can see when your device was last located. 

Unfortunately, you can’t track the location of your Mac over time: Unlike the Lost Mode available to iOS devices, Find My Mac shows only the most-recent location of your computer.

However, there are various options that you have thanks to Find My Mac. 

What can I do once Find My Mac has located my Mac? 

You can Play a Sound, Lock the Mac, or Erase the Mac. Playing a sound would be a handy way to locate a Mac that it turns out if at home after all. Be warned, it’s loud! 

You can remotely lock your Mac. When you do this the computer will shut down. Next time someone attempts to start up the Mac, it will boot into recovery mode and ask for the passcode; if you opted to display a message, that message will also appear on the same screen. Once you’ve entered the correct passcode, the Mac will reboot normally.

The final option is Erase Mac. As you might expect, this feature lets you completely erase—securely—all data and settings from your Mac. It also sets a four-digit passcode that lets you regain access to your Mac if you ever recover it. You should use the Erase Mac option only as a last resort. 

What if Find My Mac doesn’t locate my Mac?

If the service can’t locate your Mac, you still have the option of playing a sound, remotely locking the computer, or remotely erasing it, but these actions won’t take effect until the Mac connects to the Internet. To receive an email notification when your Mac does come online again, select the Notify me when found checkbox.