What is the “keyID” when using APNs push service

Question

Usually there are 3 info I need to provide, to use Apple APNs: key, keyId, teamId, like here.

I understand key (pem file location) and

Answer 1

key: 'apns.p8',   // Path to the key p8 file
keyId: 'ABCDE12345', // The Key ID of the p8 file (available at https://developer.apple.com/account/ios/authkey/)
teamId: 'ABCDE12345', // The Team ID of your Apple Developer Account (available at https://developer.apple.com/account/#/membership/)

You can find more on : https://eladnava.com/send-push-notifications-to-ios-devices-using-xcode-8-and-swift-3/