A Refresh Token is an opaque token that contains the information required to obtain a new Access Token. A Refresh Token is long-lived as opposed to an Access Token and ID Token.
A refresh token is an OAuth 2.0 specific token. It is issued as part of the authorization flow.
However, it is only issued when the client uses the
authorization_code grant type and if the 'Issue refresh tokens' option is selected in the web client configuration.
For mobile applications refresh tokens are issued by enabling the 'PIN authentication' in the app configuration page.
Refresh tokens can have a validity specified, so that those are revoked upon usage after certain amount of time.
Note: Please make sure that Refresh Tokens are stored securely and they are not leaked. Leaking refresh tokens basically means that a user account can be compromised.