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Both the id token and the access token usually are only valid for a number of seconds as indicated in the exp claim. In order to prolong the access token, there is the concept of a refresh token that can be user used to request a new access token without the users interaction. This allows an application to act on behalf of the user even beyond the users interaction. This is done by issuing a refresh token to the application. The application then can exchange that refresh token for a new access token.
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