Customizing Your Android Device - Running Android: Using Your Phone and Tablet for Work and Play - page 178

Once you have a lock screen set up, you can customize it with widgets if your device is
running Android 4 (Kitkat). To customize your lock screen, drag right from the upper left
side of the screen (this area is briefly shown when you wake up the device). Tap the large
+ icon to show the widgets available for the lock screen (not all are), then scroll up and
down to see more widgets. Tap any widget to add it. For some widgets, you'll be taken to a
configuration screen to set it up.
To remove a widget, long-press it and drag it to the Remove area at the top of the screen.
When the widget turns red, lift your finger to delete the widget. You can add more than one
widget to the lock screen, then swipe left and right to view them. The most useful widgets
are ones that show date, time, weather, battery charge, and other status information that
doesn't require interaction from the user.
To remove a widget, long-press it and drag it to the Remove area at the top of the screen.
When the widget turns red, lift your finger to delete the widget. You can add more than one
widget to the lock screen, then swipe left and right to view them. The most useful widgets
are ones that show date, time, weather, battery charge, and other status information that
doesn't require interaction from the user
Starting with Android 5 (Lollipop), widgets can no longer be added to the lock screen. But
live wallpapers can display changing information- see below.