2020 / FEBRUARY / 27

1XX Response Codes

What is a 1xx Response Code?

1xx response typically consists of a HTTP status line, a header and is terminated by an empty line. 1xx status codes are only defined in version HTTP/1.1 and not supported by the previous HTTP/1.0 version. Hence, web servers should not respond with 1xx code to an HTTP/1.0 client.

As 1xx HTTP codes are only meant for informational purposes, browsers and user agents will not process and show these response codes on the front end screen like other series of response codes. Browsers ignore these status codes and continue to process the remaining part of the requests. There are only four status codes used in the 1xx series:

100 – Continue
101 – Switching Protocols
102 – Processing
103 – Early Hints

What does the 1xx Response Code Look Like?

HTTP Status codes that come under the 1xx category are considered informational status codes. When the status code is informational in nature it will only tell the user or software agent that the request has been obtained. For instance, you may only encounter the status code 100. But you are completely unaware of the exact cause of the appearance of status code.

Guide to 1xx Response Codes-

Some of the most common HTTP 1xx status codes are listed below:

S no.	Response Code	Response Name	Description
1	100	Continue	The server has received the request headers and the client should proceed to send the request body. To have a server check the request's headers, a client must send Expect: 100-continue as a header in its initial request and receive a 100 Continue status code in response before sending the body.
2	101	Switching Protocols	The requester has asked the server to switch protocols and the server has agreed to do so.
3	102	Processing	This code indicates that the server has received and is processing the request, but no response is available yet.
4	103	Early Hints	Used to return some response headers before the final HTTP message.

Unofficial Codes

S no.	Response Code	Response Name	Description
1	103	Checkpoint	Used in the resumable requests proposal to resume aborted PUT or POST requests.

Conclusion

Web servers send 1xx series HTTP status codes are only meant for informational purposes. We have discussed above the list of 1xx HTTP status codes for informational responses returned by a web server in response to HTTP requests from the client browser.