HTTP status code 401 indicates what type of error?

The correct answer is that HTTP status code 401 indicates "Unauthorized Access." This status code is part of the 4xx class of status codes, which are used to indicate client errors. Specifically, a 401 error means that the client request has not been applied because it lacks valid authentication credentials for the target resource. In other words, when a server responds with a 401 status code, it is telling the user that they must provide valid credentials (such as a username and password) to access the requested resource.

To clarify the concept further, this status is often seen in API calls and web applications where authentication is required. For instance, if a user attempts to access a secure API endpoint without providing the necessary authorization tokens or credentials, the server will respond with a 401 error to signal the need for proper authorization.

Understanding the meaning of the 401 status code is crucial for developers, especially when dealing with secure applications and APIs, as it emphasizes the importance of implementing authentication mechanisms to protect sensitive resources.