Difference between id_token and access_token

Questions
1

On this section from Validate Access Tokens | Okta Developer, it says

it is important that the resource server (your server-side application) accepts only the access token from a client. This is because access tokens are intended for authorizing access to a resource. ID Tokens, on the other hand, are intended for authentication.

On this section from Validate ID Tokens | Okta Developer, it says

The ID token contains information about a user and their authentication status. It can be used by your client both for authentication and as a store of information about that user. One OIDC flow can return both access and ID tokens.

I read a few docs on this, and my understanding is with the introduction of OIDC (on top of OAuth 2.0), the differences between ID Token and access_token have been smaller, is that right?

Best

2

Hello! The introduction of OIDC as an OAuth extension is what introduced ID tokens.

ID tokens exist for authentication purposes and are mainly used client-side. Due to the fact that they contain additional user information via claims, they are useful for rendering that information to a page. For example, at a /dashboard endpoint in your app you might have a template setup that looks similar to this pseudo-code:

<Navbar> 
  <Dropdown>
    {{ id_token.claims.email }} 
  </Dropdown>
</Navbar>

<Dashboard>
  Hello {{ id_token.claims.givenName }}!
  <Button onclick=callToOrdersAPI>See Order History</Button>
</Dashboard>

If the user then clicks on the button to see their order history, this is where the access token comes into play for authorization. In this scenario, the callToOrdersAPI method makes a call to a protected API that contains user order information. The request would contain the access token in the authorization header, and the orders API would attempt to validate the access token to determine whether the requested information can be returned.

Does this make sense?

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