OAuth2 Authentication Flow

**Context**: 
OAuth 2.0 is an industry-standard authorization framework that allows a client application to access a protected resource on behalf of a resource owner. The OAuth2 authentication flow is a critical component of modern web and mobile applications, enabling secure and delegated access to protected resources.

**Detailed Instructions**: 
Design a detailed, step-by-step OAuth2 authentication flow for a web application that integrates with a third-party API. The flow should include the following components:
1. Client registration: Describe the process of registering the client application with the authorization server, including the required information and the issuance of a client ID and client secret.
2. Authorization request: Outline the steps involved in redirecting the user to the authorization server to obtain consent, including the required parameters and the authorization endpoint.
3. User authentication and authorization: Explain the process of user authentication and authorization on the authorization server, including the user's interaction with the authorization server and the resulting authorization code.
4. Token request: Describe the steps involved in exchanging the authorization code for an access token, including the required parameters and the token endpoint.
5. Access token usage: Outline the process of using the access token to access the protected resources on the third-party API, including the required headers and parameters.
6. Token refresh: Explain the process of refreshing the access token when it expires, including the required parameters and the token endpoint.

**Output Format**: 
Provide a detailed, step-by-step guide to the OAuth2 authentication flow in a numbered list format, with each step including a brief description and any relevant technical details, such as HTTP requests and responses, headers, and parameters. The output should include diagrams or flowcharts to illustrate the authentication flow, if possible.

**Examples**: 
Include examples of OAuth2 authentication flows for popular third-party APIs, such as Google, Facebook, or GitHub, to demonstrate the practical application of the OAuth2 protocol. Provide code snippets in a programming language of your choice (e.g., Python, Java, JavaScript) to illustrate the implementation of the OAuth2 authentication flow. 

For instance, provide an example of how to use the `requests` library in Python to send an authorization request to the Google OAuth2 endpoint, or how to use the `passport` library in Node.js to handle the OAuth2 authentication flow with Facebook. 

Ensure that the examples are concise, readable, and well-documented, with clear explanations of the code and its purpose in the OAuth2 authentication flow.