Description: The HTTP status code 401 ‘Unauthorized’ is a response indicating that the request made by the client requires user authentication. This code is part of the specification of HTTP status codes, which are used by web servers to communicate the result of an HTTP request. When a server returns a 401 code, it means that the client has not provided valid credentials or that the provided credentials do not have permission to access the requested resource. This code is common in web applications that require login, where access to certain areas is restricted to authenticated users. Additionally, the 401 code may be accompanied by a ‘WWW-Authenticate’ header, which provides information on how the client can authenticate. This mechanism is fundamental for web security, as it allows servers to protect sensitive resources and ensure that only authorized users can access them.
History: The 401 status code was defined in the HTTP/1.0 specification in 1996 and has been maintained in subsequent versions of the protocol. Its inclusion in the standard was part of a broader effort to establish a clear communication framework between clients and servers on the web. As the web grew and evolved, the need for authentication became more critical, leading to the widespread adoption of this code in applications requiring restricted access.
Uses: The 401 code is primarily used in web applications that require user authentication. It is common in sites offering exclusive content, such as streaming platforms, social networks, and online banking services. It is also used in APIs that require access tokens or credentials to interact with protected resources.
Examples: An example of using the 401 code is when a user tries to access a website or resource that requires login without being authenticated. The server will respond with a 401 code and a message indicating that authentication is required. Another example is in a REST API, where a client attempting to access a protected resource without a valid authentication token will receive a 401 code.
