As of January 2022, with 4.55 billion people using social media, many applications incorporate social sign-ins that utilize OAuth 2.0 for seamless user onboarding. OAuth 2.0 is crucial for both authentication (authn) and authorization (authz), though it is primarily a standard for authorization, often misunderstood by developers as encompassing authentication. Implementing OAuth 2.0 effectively requires understanding scopes, client IDs, consent screens, and proper server management, typically involving Google Cloud services. In Android applications, particularly those using Google sign-in, the process involves configuring the Google SDK, updating dependencies, setting up OAuth Client ID, and managing the OAuth consent screen to ensure secure and efficient user authentication. Additionally, the use of PubNub can enhance real-time interactivity and manage notifications across various platforms, leveraging Google's cloud services for high reliability and scalability.