Public vs Private Certificates in Azure

Question

I was going through Azure docs for App Service and found the terms Public Certificate and Private Certificate. I am having trouble understanding what these term mean.

I read somewhere that public certificates are for use on internet and private certificate are for securing internal network communication.

But

The below snippet from Azure documentaion further adds to the confusion:

Public certificates are not used to secure custom domains, but you can load them into your code if you need them to access remote resources.

So my question is:

1. What does private and public certificate mean in azure?
2. What does private and public certificate mean in normal sense?
3. Why cannot I use public certificates to secure custom domains in Azure App Service?

Answer 1

Private certificates is used to when you encrypt, often the connection. So if you need https on www.yourdomain.com you use a private certificate.

Public is used if you need to connect to some service that uses a certificate that's not included in MS trusted certificates. You might need to call some internal domain that uses self-signed certificates, or for some reason don't use certificates commonly trusted.