Most people just see this as what is displayed in a browser, although some browsers do hide this but it stands for Hyper Text Transfer Protocol and if you see an S on the end then that means the communication is encrypted. There is a huge amount that can be said and indeed has been written about HTTP, so there is no value in my repeating that, so I will defer to Mozilla and recommend reading HTTP | MDN.

One area I keep having to try and remember is HTTP Response Codes. When any software sends a request to a server via HTTP the server will respond and include a response code. They are categorised as follows:

  • 1xx (Information) - the code is for information
  • 2xx (Success) - processing was successful but that includes no or partial content
  • 3xx (Redirect) - a different request is required as something hs probably moved
  • 4xx (Client Error) - either the request was invalid, or there was a permissions or location issue
  • 5xx (Server Error) - the request was fine but an error happened within the server
For a complete list and full explanation see HTTP response status codes - HTTP | MDN.

The current standard is HTTP 1.1, there is also HTTP/2, which is designed to reduce latency by changing how the data is packaged and transported, it does not change the status codes, header fields and so on.