Refresher on access tokens

Recall from the A closer look at access tokens section in Chapter 3, Four Easy Steps, an access token is an opaque string given to clients that provides temporary access to a protected resource. More specifically, they represent a specific scope of permissions and duration of access for a particular client application to use, all of which are enforced by the service provider. This can be thought of simply as an encapsulation of the user's authorization to access or modify a particular scope of their resources.