iCloud: Find My iPhone

The iCloud web application that you can use to locate, play a sound on, track, remotely lock, or erase your lost iOS device or Mac computer.

To use Find My iPhone, you need to set up Find My iPhone on each iOS device and Mac before it is lost. Find My iPhone requires iOS 5 or later (iOS 6 required for tracking) or OS X v10.7.5 or later, respectively.

You can use Find My iPhone at icloud.com/find on any Mac or Windows computer, or download and use the free Find My iPhone app on an iOS device.