Nobody wants to go through the ordeal of a lost smartphone, but it happens. There are tracking apps available to help owners locate their lost or stolen phones via GPS, but in some instances, just having your contact info on your phone might do the trick.
Many Android smartphones, like the Samsung Galaxy S3 and Note II, have an Owner Information setting that will display your contact info on the lock screen. If you lose your smartphone and a Good Samaritan finds it, they'll be able use the owner information you've entered to reunite you with your precious device.
To set Owner Information on a Samsung Galaxy S3, go to Settings > Lock Screen > Owner information. On other Android smartphones, you may find the Owner Information setting under Settings > Security, or similar.
Enter your contact information in the box, like your name and an alternate phone number or e-mail address. Before pressing the OK button, make sure the box next to "Show owner info on lock screen" is checked.
Hopefully you'll never lose your smartphone, but if you do, wouldn't it be a pleasant surprise to have it returned by someone who was eager to return it to you?