Q:

Microsoft Graph API - how to get access token without Authorization Code?

I want my Web API to get an Access Token to then call Microsoft Graph API. I've gone through a few documents and threads but they all talk about a POST method that asks for a Client ID and App Secret created when registering the app on AAD. 
I'm following this document here.
My problem is:
What is client_credentials? Where should I get it from? I thought the API is supposed to be working with the secret and the client I'd only.
I appreciate your help. 

A:

There's 4 parameters in the HTTP request:

grant_type: in this case, the value is "client_credentials"
client_id: The client id of your app
client_secret: The client secret of your app
resource: The identifier of the API you want a token for, in this case https://graph.microsoft.com

So only client id and secret are needed from your app.
If you use v2 endpoint / MSAL, note there is no resource parameter.
Instead you would use scope=https://graph.microsoft.com/.default.

