HTTP 1xx Status Codes: An Overview

HTTP 1xx Status Codes: An Overview
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In the realm of web server communications, understanding HTTP status codes is fundamental. These are sent by a web server in response to a client’s HTTP request and help discern the nature of the request’s result.

HTTP response codes fall into five distinct categories, each serving a unique purpose:

  • 1xx Informational: These relay preliminary information following the initial HTTP request.
  • 2xx Success: These indicate that the client’s request was received, understood, accepted, and processed successfully by the server.
  • 3xx Redirection: When the requested resource resides at a different location, these codes instruct the client to access the resource from that new location.
  • 4xx Client Error: These reflect errors primarily originating from the client side. This usually happens when the client lacks the necessary parameters to reach the requested URL.
  • 5xx Server Error: Lastly, these represent situations where the server was unable to process a seemingly valid client request.

Understanding each category and its associated status codes equips SEO professionals with the knowledge to optimize web communications, diagnose issues, and enhance the overall browsing experience.

So, let’s explore in detail HTTP 1xx status codes.

HTTP 1xx Status Codes as a Bit of SEO Optimization

HTTP 1xx status codes play a significant role in web communications’ smooth and efficient functioning.

They are classified as informational, essentially acting as a sort of ‘heads up’ between the client and the server. They provide provisional responses which encourage the client to continue the request.

Here’s a quick rundown of what each HTTP 1xx status code means:

100 Continue

This is considered as a green light. The server has successfully received the request headers, and now the client has the go-ahead to send the request body.

101 Switching Protocols

This one demonstrates the flexibility of HTTP communication. Upon the client’s request, the server prepares to switch protocols and sends this to acknowledge the process.

102 Processing (WebDAV)

This shows that the server is like a diligent worker. It has received the request and is busy processing it, even if there’s no immediate response available.

103 Early Hints

This is valuable for enhancing the user experience. Used primarily with the Link header, it enables user agents to start preloading resources while the server is still preparing the final response.

Understanding these 1xx codes can provide valuable insights into your server’s efficiency and your website’s loading times, both of which are vital factors in SEO.

Remember, every tiny bit of optimization contributes to the overall visibility and success of your site.


HTTP status codes, including the less common 1xx, are key to understanding web communications. These preliminary 1xx codes serve as cues for continued interaction between the client and server, each with a distinct meaning. Grasping these codes allows SEO professionals to optimize server efficiency and website load times, thereby enhancing overall website visibility and success.

They are crucial tools in an SEO professional’s toolkit for ensuring optimal web communication and a superior user experience.

1xx preliminary is an informational code indicating that the server received the request and the client should wait for further replies before proceeding.
The 1xx status codes in FTP represent positive preliminary replies, meaning the action has been initiated and expects another reply before a new command. If you encountered the error "1xx" in the context of FTP, it could be specific to the FTP server or client you are using or a misinterpretation of the error.
It provides information that an action has started, and another reply will follow before the client can proceed with a new command.

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