The OAuth 2.0 is an authorization technique available in Postman. Here, we first obtain a token for accessing the API and then utilise the token to authenticate a request. A token is used to ensure that a user is authorised to access a resource in the server.
If we make an attempt to access a secured URL without the token, a Response code 401 Unauthorized shall be obtained. To start with, the application passes an authorization request for the end user to access a resource.
As the application allows the user access, it asks for an access token from the server by providing user information. In turn, the server yields an access token. The client can then access the secured data via the access token.