HTTP status codes | Informational Responses

The HTTP status codes are used to indicate that any specific HTTP request has successfully completed or not. The HTTP status codes are categorized into five sections those are listed below:

• Informational responses (100–199)
• Successful responses (200–299)
• Redirects (300–399)
• Client errors (400–499)
• Server errors (500–599)

There are four Informational Responses those are Continue, Switching Protocols, Processing, and Early Hints. All of them are described below:

• 100 Continue: The HTTP 100 Continue Informational Response status code is used to inform the client that till now everything is OKAY with the request. If the work is done then the client will ignore it if it’s not done yet then the client will proceed with the other requests. The server needs to send a final response when the request has been completed.
  When the request contains the Expect header field that includes 100-continue expectation, the 100 response indicates that the server waiting to receive the request payload body. The client does not need to send the request-header with the 100-continue expectation. If it does not wish to send a request body.
  Status:

  100 Continue

• 101 Switching Protocols: The HTTP 101 Switching Protocol Informational Response status code is used to indicate the protocols that are going to switch for the client request which includes the upgrade request header for the protocols. This status code can be used with the WebSockets.

  Status:

  101 Switching Protocols

  Example: Performing with the websockets.

  HTTP/1.1 101 Switching Protocols
  Upgrade: websocket 
  Connection: Upgrade

• 102 Processing: The 102 Processing Informational Response status code is used to indicate that the server received the request and working on the request but in response, there is nothing till now.
• 103 Early Hints: The 103 Early Hints Informational Response status code is used with the link header to allow the User-Agent to reloading the resources when the server is preparing a response. So basically when the server is working on to prepare the response then, the 103 Early Hints forcefully reloading the resources so the server can have few times on preparing a response.
  Status:

  103 Early Hints

Supported Browsers: The browsers compatible with the HTTP status codes Informational Responses are listed below:

• Google Chrome
• Internet Explorer
• Firefox
• Safari
• Opera