Which types of tokens are used in OAuth for secure access?

The use of access tokens and refresh tokens in OAuth is fundamental to the secure authorization process within the protocol. An access token is a credential that can be used by the client to access protected resources on behalf of the user. It provides the necessary permissions to perform actions like fetching user data or performing transactions within a specified time frame.

The refresh token, on the other hand, allows the client to obtain a new access token without requiring the user to re-enter their credentials. This helps maintain a session while adhering to security best practices, as the refresh token can be granted longer expiry times and typically used only to request new access tokens. This two-token mechanism enhances security by minimizing the chances of an access token being compromised, as it is short-lived.

This structure enables a seamless user experience while maintaining secure access controls, illustrating why access tokens and refresh tokens are pivotal in OAuth's architecture for authorized communication between clients and resource servers.