HTTP Response Status Codes: Informational (100 – 199)

HTTP response status codes provide crucial information about the outcome of a client’s request to a web server. These codes are divided into five classes, each serving a specific purpose.

In this blog post, we will focus on the first class – Informational Responses (status codes 100 – 199). These codes are used to communicate provisional information, indicating that the request is still being processed or that further action is required before a final response can be sent. Let’s explore each of these informational status codes in detail.

Table: HTTP Response Status Codes – Informational Responses

Status Code	Name	Description	Example
100	Continue	The server received the request headers and is waiting for the client to send the request body.	HTTP/1.1 100 Continue
101	Switching Protocols	The server has agreed to switch protocols as requested by the client.	HTTP/1.1 101 Switching Protocols
102	Processing	The server is still processing the request, but no response is available yet.	HTTP/1.1 102 Processing
103	Early Hints	Used to return some response headers before the final response is ready.	HTTP/1.1 103 Early Hints

HTTP 1xx Status Codes (Informational):

1. 100 Continue:
   • Description: The server acknowledges that it has received the initial part of the request and indicates that the client should proceed with the rest of the request.
   • Example: HTTP/1.1 100 Continue
2. 101 Switching Protocols:
   • Description: The server informs the client that the requested upgrade to the protocol is being received, and the server will switch protocols to those defined in the Upgrade header field.
   • Example: HTTP/1.1 101 Switching Protocols
3. 102 Processing:
   • Description: The server indicates that it has received the request and is still processing it. This status code is typically used for long-running requests, and the client should continue to check for updates.
   • Example: HTTP/1.1 102 Processing
4. 103 Early Hints:
   • Description: Used to return some response headers before the final response is ready. This allows the client to start processing the headers while the server prepares the actual response.
   • Example: HTTP/1.1 103 Early Hints

Informational responses are primarily used to establish communication between the client and server during the early stages of a request. They provide assurance that the server has received the request and is processing it, or they may indicate an upcoming protocol switch. However, these responses do not carry the actual data that clients are seeking.

It’s important to note that, in most cases, these informational responses are handled automatically by the client (e.g., web browsers) and do not require explicit handling in typical web development scenarios.

In conclusion, understanding HTTP response status codes, including the Informational Responses (100 – 199), is vital for web developers and system administrators.

While these codes may not directly provide the requested content, they play a crucial role in establishing communication and signaling the progress of the request.

Keep this guide handy as a reference to navigate the world of HTTP response status codes effectively.

Next, we will explore the Success Responses (200 – 299), which indicate that the client’s request was successfully received, understood, and accepted. Happy coding!

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References

https://developer.mozilla.org/en-US/docs/Web/HTTP/Status