For checking information without unlocking
Instead of unlocking your phone every time just to check the weather or your schedule, placing a widget on your lock screen lets you see the information you need the moment you turn on the screen.
Also check out Android's notification history
If you're worried about missing a notification, it's worth looking into how to use Android's notification history to catch anything you missed.
Frequently Asked Questions
Can every Android device use lock screen widgets?
Support and menu locations vary by manufacturer and Android version, so the option to add a widget may not even appear on older devices.
Does adding several widgets drain the battery faster?
Adding multiple widgets that refresh in real time can increase battery use somewhat, so it's best to add only the ones you check often.