Token-based authentication is a method for verifying your identity when you access an application or service. Instead of entering your username and password every time, you receive a unique digital token after you log in. You send this token with each request to prove who you are.

Token-based authentication is important because it keeps your credentials safe and makes it easier to manage secure access. With tokens, you can control how long someone stays logged in, easily log users out, and limit what actions they can perform. This approach is widely used in modern web and mobile applications to improve security and user experience.

How Token-Based Authentication Works

1. Issuing a Token

• You send your login details, such as a username and password, to the authentication server;
• If your credentials are correct, the server creates a token — a special string of letters and numbers;
• The server sends this token back to you.

Example: You log in with your username and password. The server replies with a token like eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9....

2. Using a Token

• You include the token in the headers of your API requests, usually in the Authorization header;
• The token proves that you are authenticated and allowed to access certain resources.

Example: You make a request to /api/orders with a header: Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9....

3. Verifying a Token

• Each time you make a request, the API gateway checks if your token is valid;
• If the token is valid and not expired, you are allowed to use the API;
• If the token is missing, invalid, or expired, access is denied.

Example: If your token is valid, you get the order details. If it is not, you receive a 401 Unauthorized error.

Tokens are used to prove your identity. They are issued when you log in, included in your requests, and checked every time you try to access a resource. This helps keep your APIs secure and ensures only authorized users can access them.