Information being transmitted over unsecure Wi-Fi (like in a hotel lobby or coffee shop) is vulnerable to being stolen. Some of the information that you are storing or sharing from your device, like the time you usually leave the house in the morning, your health history, and financial information could be useful to cybercriminals and should be kept safe.
Be cautious when using public Wi-Fi networks as they are not always secure. It is safest to use trusted Wi-Fi connections that are password protected. Turn off Wi-Fi, GPS and Bluetooth when you are not using them.