One account for all your Apple devices (such as your iPhone, iPad, MacBook or iMac) and Apple services. Apple services include iCloud (which stores device backups, photos, documents and passwords), App Store (for the apps on your iPhone/iPad), iMessage and more. To see your Apple ID information go to Settings ❯ Apple ID on a device, or from a browser go to www.icloud.com, sign in with your Apple ID, then profile icon ❯ ‘Manage Apple ID’