Apple ID
The account you use to access Apple services such as the App Store and iCloud. It includes the email address and password you use to sign in as well as all the contact, payment, and security details you use across Apple services.
If you’re signed in to iCloud, your Apple ID appears below your name in your computer’s System Preferences or your device’s Settings.
On a Mac: Choose Apple menu
> System Preferences, then click Apple ID (to the right of your name). Or, if you’re using macOS 10.14 or earlier, click iCloud 
instead.On iPhone or iPad: Tap Settings > [your name].
On a Windows computer: Open the iCloud Control Panel.
For more information, visit the Apple Support site.