Truecaller is an app which trace and display the details of incoming calling person. From this you can find the person behind the number, because the truecaller has billions of mobile numbers are registered on it from all over the world. As phone ringing & start at the screen as soon as the first Truecaller find the whether users that are Facebook, Gmail or Yahoo ID to log calls from these 3 networks. You can find details of any unknown caller easily. If person not registered on Truecaller you will not find any details of the caller. In truecaller mobile phone numbers and locations can be searched. Android app is good and barely of 7mb. Beside good features truecaller has some cons. You cannot trace any landline. Some people gives fake details on truecaller.