Smart lock is a feature that allows you to easily unlock your phone.
You can set it to keep your phone unlocked when you have a trusted Bluetooth device connected to it,
when it's in a familiar location like your home or work, or when it recognizes your face.
Trusted source options:
- Device: Bluetooth or NFC
- Place: e.g. Home and/or Work address. You can also set customized places
- Face: set your face as trusted
When you have added one or more of these sources, your screen lock (e.g. Pin code, Pattern) will change to 'swipe'.
Smart Lock was first introduced in Android 5.0
Also read: Smart Lock: How to set up a trusted device, place and/of face?