When you interact with the web, every request your browser or application sends to a server receives a response. These responses include HTTP status codes, crucial indicators of the request’s outcome. Among these, the 2xx success codes signal that your request was successfully received, understood, and accepted by the server. But what does each specific 2xx code mean, and how can you interpret them in your web development or server management tasks? This article will delve into each of the HTTP 2xx success response codes, providing a comprehensive understanding of their nuances and practical applications.
Decoding the 2xx Success Family
The 2xx range in HTTP status codes is dedicated to signaling success. However, “success” in web interactions isn’t always a simple concept. Different 2xx codes offer more granular details about the nature of the successful request. Let’s explore each code individually to understand their specific meanings.
200 OK
The most common and fundamental success code is 200 OK. This code simply means that the request has succeeded. The exact meaning of “success” depends on the HTTP method used in the request:
- GET: The resource has been fetched and transmitted in the response body.
- POST: The resource describing the result of the action is transmitted in the response body.
- PUT/DELETE: The resource describing the action’s outcome is transmitted in the response body.
Essentially, 200 OK is the standard positive response for successful HTTP requests.
201 Created
The 201 Created status code indicates that the request was successful and, as a result, a new resource has been created on the server. This response is typically sent after POST requests, or some PUT requests.
For example, if you submit a form to create a new user account, upon successful creation, the server should respond with a 201 Created status. Often, this response includes a Location header, which provides the URL for accessing the newly created resource.
202 Accepted
The 202 Accepted response signifies that the server has received the request, but has not yet processed it. The request has been accepted for processing, but the processing has not been completed. This is an important distinction from 201 Created or 200 OK.
A 202 Accepted response is non-committal, as HTTP doesn’t provide a standard way to send a later asynchronous response to indicate the outcome of the request. This code is best suited for operations that might take a considerable amount of time to process, where providing immediate feedback is not feasible, such as batch processing or requests handled by another server or process.
203 Non-Authoritative Information
The 203 Non-Authoritative Information response code indicates that the information returned in the payload is not from the origin server, but rather from a proxy or local copy. This implies that the returned metadata might not be exactly the same as what resides on the origin server.
This code is commonly used in scenarios involving mirrors or backups of resources. While the request is successful, the client should be aware that the information provided might not be the most up-to-date version available at the original source. In most situations, a 200 OK response is preferred over 203 unless explicitly serving from a mirror or backup.
204 No Content
The 204 No Content status code indicates that the server has successfully processed the request, but there is no content to send back in the response body. Unlike 200 OK, a 204 response will not contain a message-body.
This is useful when the client doesn’t need to update its view – for example, in response to a successful DELETE request, or when you want to update client-side metadata without needing to reload the entire page. The user agent may update its cached headers for this resource based on the new headers in the 204 response.
205 Reset Content
The 205 Reset Content response code is similar to 204 No Content, but it also instructs the user agent to reset the document view. This means the browser should reset the document that initiated the request.
This code is primarily used after a user has submitted input to a form to clear the form fields, prompting them for new input. It signals a successful action and prepares the client-side for further interaction.
206 Partial Content
The 206 Partial Content status code is sent when the server is fulfilling a range request from the client. This indicates that the server is only sending a portion of the requested resource, as specified by the client using the Range header.
This is frequently used for efficiently handling large files, such as video or audio, allowing clients to download only segments of the file, which is crucial for streaming and resuming interrupted downloads. The response must include a Content-Range header indicating the range of the content being returned.
207 Multi-Status (WebDAV)
The 207 Multi-Status response code is specific to WebDAV (Web Distributed Authoring and Versioning). It conveys status information for multiple resources in situations where a single request may affect several resources.
For example, in a WebDAV PROPFIND request, which retrieves properties of resources, a 207 Multi-Status response might be returned if the request involves multiple resources, each potentially having a different status. The response body is an XML message containing individual status codes for each resource.
208 Already Reported (WebDAV)
Also specific to WebDAV, the 208 Already Reported status code is used within a DAV:multistatus response to avoid repeatedly enumerating the internal members of multiple bindings to the same collection.
Essentially, it’s used to optimize WebDAV responses by indicating that a resource has already been included in a previous part of the response, preventing redundant reporting of the same resource within a multi-status response.
226 IM Used (HTTP Delta encoding)
The 226 IM Used status code is used in conjunction with HTTP Delta encoding. It signifies that the server has fulfilled a GET request for the resource, and the response is a representation of the result of one or more instance-manipulations (“delta encoding”) applied to the current instance.
Delta encoding is a way to efficiently update resources by sending only the differences (deltas) between versions, rather than the entire resource. 226 IM Used confirms that the server used delta encoding and the response contains the delta-encoded resource.
Conclusion: Mastering Success with 2xx Codes
Understanding HTTP 2xx success response codes is crucial for anyone working with web servers and applications. While they all signify successful requests, each code provides specific information about the nature of the success, from simple data retrieval (200 OK) to resource creation (201 Created), partial content delivery (206 Partial Content), and specialized WebDAV or delta encoding scenarios. By correctly interpreting these codes, developers can build more robust and efficient web applications and services, ensuring seamless communication between clients and servers.
