Screen time record all the activity while your device turns on and accessing different app and settings. Screen Time also works like the Parental control you can set the limit on app access, Notification control. Also, you can Generate Screen Time report for today and Last 7 Days and more.
Important functions in Screen Time are Downtime, App Limits, Always Allowed, and Content & Privacy Restrictions. See this article created with my iPhone X running on iOS 12.
Steps for Turn on or Disable Screen Time on iPhone/iPad in iOS 12
Turn off Screen Time on iPhone/iPad in iOS 12
Go to the Settings app on your iPhone/iPad
Next to the Settings > Screen Time
Scroll down and Tap on “Turn off Screen Time”. Enter the Verification passcode.
[Also Read: How to Limit Kid’s Screen Time on iPhone, iPad ]
Turn on Screen Time settings on iPhone
Go to the “Settings app” on iPhone.
In Settings, Scroll down and See “Screen Time” option at near to Do Not Disturb.
Tap on “Turn on screen Time”. The first screen will allow you to set up this phone as of your kids. You can go with option “Set up as Parent” otherwise “Continue”.
Tap on it and Tap on your iPhone Name > See the General Screen time overview based on settings. Default settings will see the Most Used app, Pickups, Notification count and more for Today and Last 7 Days switch from top tab.
Customize App allow or restrict from Screen time on iPhone
Downtime: By Enable or Turning on this toggle, you can set a schedule for time away from the screen. During downtime, only apps that you choose to allow and phone calls will be available.
App Limits: Set Daily time limits for app categories you want to manage. App limits reset every day midnight.
Always Allowed: Always Allowed apps are available during downtime, or if you selected the “All apps & Categories” App limit.
Content & Privacy Restrictions: Manage security data in your hand.
Above steps are used for turn on or turn off screen time on iPhone X/ iPhone 8/8 Plus, iPhone 7/7 Plus running on iOS 12.