The most important feature of the iPhone's “Find My Phone” app is its ability to track the location of the device, updating it every 30 seconds on a live feed. Another feature is "Play Sound," which gives you an audio cue even if the phone is in silent mode.
In 2015, Apple updated the app to allow login capabilities from another device in the event you misplace your iPhone. You may then leave a message with your contact information on the display screen for people to contact you should they find your lost phone. You can customize the message to anything you wish to display on the screen.
You can also send a signal to the device to erase all contacts if you feel that there is no hope of finding your device or that it is stolen, ensuring that no one can view your items. You can remotely lock the device as well and put a passcode on the phone. Finally, the person using the device must use your Apple ID and current password to unlock it for further use in the event you erase your phone remotely. Your iPhone must have at least the iOS 7.0 operating system installed for you to make use of these features.