In the past, when you lose your handphones, it would be very difficult to find or even trace where your phone is. But nowadays, with the advancement in technology, smartphones have become the norm . There are many applications that can be downloaded using smartphones which can help in tracing your smartphone.
For iOS
Find My iPhone 
Enable Find My iPhone in settings. Then if you misplace your iPhone, you can sign in to me.com from any computer web browser or using the Find My iPhone app on another iPhone, iPad or iPod Touch to display its approximate location on a map. Also, you can write a message and display it on your screen. Your message will appear on the iPhone even if the screen is locked. You can also tell Find My iPhone to play a sound that overrides the volume or silent setting if your iPhone is nearby. You can also set a passcode lock remotely and also protect your privacy with Remote Wipe. You can initiate a remote wipe to restore your iPhone to its factory settings. When you find your iPhone back, just connect it to your computer and use iTunes to restore the data from your most rec
ent backup.
For Android
McAfee WaveSecure

Secures your mobile device and personal data in the event of loss or theft by allowing you to locate or track your device, helps prevent device misuse, and remotely locks your device and wipes your data. It enables you to back up and restore your data from the device or via an easy-to-use web portal.
Lookout Mobile Security
Use Phone Locator to locate your lost or stolen phone on a Google Map. Activate a loud alarm, even if it is on silent. When possible, Lookout will remotely enable GPS to help you find your phone even if GPS is turned off. Lock in to

myLookout.com from any web browser to locate your phone.
Therefore, if you want to secure your phone, you can install such applications to allow you to be able to prevent any unintended leakage of personal information and also to track your phone.
By Zi Qiang