Image source :- https://dev.office.com/blogs/microsoft-graph-or-azure-ad-graph
Microsoft graph API(Application Programming Interface) is a great tool that provides access to multiple Microsoft products such as mail, calendar, contacts, documents, directory, devices etc may be accessed from single endpoint.
It allows user apps to Intgrate with Single endpoint so that it involes less research by developer and more productivity.
In order to have access to this API you need to have Azure cloud credentials.
To access this Api on postman you first need to
1.Sign up for azure portal and login
2. create an app in azure active directory get client Id and client secret
3.Set callback in return url to https://www.getpostman.com/oauth2/callback
4. open postman or any other rest API testing tool
5. set Auth 2.0 parameters as
Token Name : – {anything you want just a naming convention}
Auth URL : – https://login.windows.net/common/oauth2/authorize?resource=https%3A%2F%2Fgraph.microsoft.com
Token URL : – https://login.windows.net/common/oauth2/token
Client ID : – {client id generated from azure app}
Client Secret : – {Secret that you got from the Azure app}
Now in order to navigate and access please refer