How can I authenticate users with third-party services, such as Google Sign-In or Facebook Login?

Before starting the tutorial, please take note of the assumptions we've made:

1. You have a basic understanding of programming languages.
2. You have an application that you want to implement social login on.
3. You are familiar with OAuth which is a standard authorization protocol used for a lot of social login services.

This tutorial provides a simple guide on how to use third-party services, such as Google Sign-In or Facebook Login to authenticate users in an application.

Setting Up Your Application

Step 1: Create a new project or use an existing one

This project is where you will be integrating the third-party login service.

Step 2: Determine which third-party services you want to use

For the purpose of this tutorial, we will be using Google Sign-In and Facebook Login for user authentication.

Integrating Google Sign-In

Step 3: Set up a Google API Console project

Before you actually start writing code to integrate the Google Sign-In service, you first need to set up a project at the Google API Console.

Step 4: Create OAuth 2.0 client ID credentials

Select your project, go to the "Credentials" section, click on the "Create Credentials" button, and choose "OAuth client ID".

Step 5: Set up the OAuth Consent Screen

Google requires that you configure an OAuth consent screen for your application. This is the screen that the users will see when they will be asked to grant permission to your app.

Step 6: Download the JSON of your OAuth 2.0 client ID

You will need these credentials the code to allow for user authentication.

Step 7: Add the Google Sign-In button to your app

Follow the official Google documentation to add the Google Sign-In button to your app.

Step 8: Send the auth code to your server

Once the user authenticates with Google, you will receive an auth code that you can send to your server to authenticate the user.

Integrating Facebook Login

Step 9: Set up a Facebook Developer account

Sign up for an account or login to your existing account at the Facebook Developer section.

Step 10: Create a new Facebook App ID

You can create a new app by clicking on the "Create App" button in the "My Apps" dropdown menu.

Step 11: Set up Facebook Login product

From the "Products" section in your app dashboard, find "Facebook Login" and set it up by following the on-screen instructions.

Step 12: Insert Facebook SDK into your code

Add reference for the Facebook SDK in your application, following Facebook’s detailed guides according to your chosen programing language.

Step 13: Implement Login Button

Use the provided code from the SDK guide to implement the login button. The button often auto encompasses the functions required to authenticate the user.

Step 14: Handle the login result

After login, you'll receive a token that is used to identify the user. You can use this token to authenticate and identify the user in your backend system.

Important note: The authentication token should not be persisted in your data storage to avoid unnecessary security risks. Always retrieve an up to date token when you need to perform an action on behalf of the user.

With both the Google Sign-In and Facebook Login set up, you can now authenticate your users using either of these services. Keep in mind permissions and data privacy while creating your applications.