2025-02-21 18:19

HTTP Status Codes and Meanings

The term HTTP originates from the abbreviation of HyperText Transfer Protocol. This term is internationally used as HTTP and is a standard protocol that defines the format and transmission rules of messages over the web. HTTP status codes are three-digit indicators that describe events occurring during the connection process between the client (i.e., the web browser) and the server. It is often mistakenly assumed that these codes are only related to errors; however, the primary purpose of status codes is to communicate the state of data exchange between the server and the client. In other words, HTTP status codes exist not only for failed requests but also for successfully executed operations. These codes are used to manage, direct, and monitor data traffic between the server and the client. They provide information to the user side.

During the process of transmitting data from the server to the user, HTTP status codes help determine whether any error has occurred, and if so, what the source of the error is. For instance, is the error a server-side 5XX issue, or did it occur due to the user entering an incorrect URL and requesting a non-existent page, resulting in a 4XX error? Additionally, has the web page been redirected, or is everything working correctly, allowing the client to view the received data properly? These questions can also be answered using status codes. For example, a 200 status code indicates successful data transmission. All these details can be analyzed by reviewing the HTTP status codes.

Why Are HTTP Status Codes Important?

HTTP status codes are essential for ensuring the proper functioning of web pages and identifying potential issues. These codes describe the state of communication between the client (browser) and the server, indicating whether data transmission has been successful or not. Website owners and developers can use status codes to detect errors and find quick solutions.

From an SEO and search engine optimization perspective, status codes also play a crucial role, as incorrect codes can affect page indexing and user experience. Therefore, proper management of HTTP status codes helps websites operate more reliably and efficiently.

Categories of HTTP Status Codes

HTTP status codes are specific indicators that represent the state of data exchange between the web server and the client. These codes are divided into five main categories, each representing different situations. Categories such as informational responses, successful responses, redirection responses, client errors, and server errors help determine whether a request was successful or why it failed. For website owners, developers, and system administrators, these codes assist in quickly identifying and resolving errors. Now, let's take a closer look at the main categories of HTTP status codes.

1xx: Informational Responses

1xx status codes are informational responses indicating that the request sent by the browser has been received and is being processed. These codes help the server provide initial feedback to the client before fully executing the request.

Status codes in the 1xx category are mainly used for large data transfers and monitoring connection status. These types of status codes are usually temporary and may require additional responses to complete the request.

Now, let's look at the main types of 1xx status codes:

100 Continue: Indicates that the request sent by the user has been acknowledged by the server and is ready for processing.
101 Switching Protocols: Confirms that the client has requested a protocol change, and the server has accepted it.
103 Early Hints: Shows that data has been circulated after the final user request.

2xx: Successful Responses

2xx status codes indicate that the request sent by the user has been successfully received, understood, and executed by the server. These codes confirm that the web page or application is functioning correctly and that data has been successfully transmitted.

The 2xx category is primarily used to indicate successful data transmission and proper server functionality.

Now, let's explore the 2xx status codes:

200 OK – A success status code indicating that the request sent by the user has been successfully processed by the server and the response has been delivered to the user.
201 Created – Indicates that the request has been successfully fulfilled by the server.
202 Accepted – Shows that the server has received the request but has queued it for processing.
203 Non-Authoritative Information – Indicates that the server has successfully received and executed the request but has not sent any content in response. Additionally, no changes or redirections should occur in the user interface (e.g., after form submission).
204 No Content – Indicates that the server has successfully executed the request but has not sent any content in response. No changes or redirections should occur in the user interface (e.g., in a completed form).
205 Reset Content – Indicates that the server has successfully executed the request and requires the user interface (e.g., a completed form) to be reset to its original state.

3xx: Redirection Responses

3xx status codes indicate that the request sent by the user must be redirected to another URL for completion. These codes are mainly used when a web page is moved to a different address or temporarily loaded from another resource. 301 Moved Permanently represents a permanent redirect, while 302 Found indicates a temporary redirection. If redirection status codes are not managed properly, they can negatively impact SEO performance and user experience.

300 Multiple Choices – Indicates that the server has multiple different resources available to fulfill the user's request, and the user must choose one.
301 Moved Permanently – Shows that a resource on the server has been permanently moved to a new address.
302 Found – Indicates that a resource on the server has been temporarily moved to a different address.
303 See Other – Indicates that a resource requested via the POST method has been reached, but the resource should be accessed using the GET method at a new URL.
304 Not Modified – Informs that the cached data in the browser has not changed and the existing version can be used.

4xx: Client Errors

4xx status codes indicate that there is an error in the request sent by the user (browser) and that the server cannot fulfill this request. These codes usually occur in cases such as entering an incorrect URL, permission issues, or requesting a non-existent page. 404 Not Found indicates that the requested page does not exist, while 403 Forbidden means the user does not have permission to access the content. If client errors are not properly managed, they can negatively impact user experience and website reliability.

400 Bad Request – Indicates that the server cannot process the request due to errors in the data sent by the user.
401 Unauthorized – Shows that the user’s authentication credentials are missing or incorrect, preventing access to the requested content.
402 Payment Required – Indicates that payment is required before accessing the requested resource.
403 Forbidden – Indicates that the server does not have permission to provide the requested information.
404 Not Found – Informs that the URL entered by the user could not be found on the server.
405 Method Not Allowed – Appears when the request method (e.g., GET, POST) used by the user is not supported by the server.
406 Not Acceptable – Indicates that the server cannot provide the requested data in a format accepted by the user’s browser.

5xx: Server Errors

5xx status codes indicate that the server is unable to process the request sent by the user and that the issue originates from the server. These errors are usually caused by internal server issues, high traffic load, or technical malfunctions. 500 Internal Server Error represents an unexpected internal server error, while 503 Service Unavailable indicates that the server is temporarily unavailable. Proper management of server errors is crucial for maintaining website reliability and uninterrupted functionality.

500 Internal Server Error – A status code returned for internal server problems and unexpected errors.
501 Not Implemented – Indicates that the server is unable to perform the requested function and cannot process the request.
502 Bad Gateway – A status code displayed when an unsuccessful response is received during communication between servers.
503 Service Unavailable – Indicates that the server is temporarily unable to provide service and is currently unavailable.