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

If one don't have Key ID at https://developer.apple.com/account/ios/authkey, he or she can follow this steps to create it:

1) Go to Developer Account aka Member Center > Certificates, IDs & Profiles > Keys / All > press the "+"

2) Enter Name and check APNs. The key is the same among your apps, so don't add app name to the key name. Click Confirm.

3) Download the key and be careful with it. Here you can see the Key ID (kid) value.