200, 301, 404, 500 & 505 - what are the most popular HTTP Status Codes?

200 OK, 301 Moved Permanently, 400 Bad Request, 500 Internal Server Error

Probably the server response codes you are most familiar with are 404 (page not found) and 500 (internal server error).

However, not every code means an error. Find out the most popular HTTP responses — both error and correct server operation.

HTTP Response Code — what is it?

Server response codes are otherwise known as information that servers send to clients — usually browsers. It can be visualized as follows:

When you open a given web page, you send a so-called request to the server (a request that is supposed to trigger a specific response — in this case, the opening of the page).

In response, the server sends a selected code that indicates how your request was fulfilled.

HTTP Response Status Codes

HTTP Status Codes or Response Codes are grouped into five categories.

1xx — Information responses

  • Information codes — beginning with the digit 1
  • They indicate that the request initiated by the browser is continuing

2xx — Successful responses

  • Success codes starting with 2
  • Success codes returned when browser request was received, understood, and processed by the server

3xx — Redirection messages

  • Redirection codes — starting with 3
  • Redirection codes returned when a new resource has been substituted for the requested resource

4xx — Client error responses

  • Client application error codes — starting with 4
  • Client error codes indicating that there was a problem with the request

5xx — Server error responses

  • Server error codes — starting with digit 5
  • Server error codes indicating that the request was accepted, but that an error on the server prevented the fulfillment of the request.

200 OK

200 OK: the request has succeeded

This is the best HTTP status code you can get. A 200-level response means that everything is working properly.

301 Moved Permanently

301 redirect: permanently moved content

If you see message 301 (moved permanently, redirect permanently), it means that the information you are looking for is in a different location.

In such a situation, the server updates the link, takes you to the new location and leads you to a status of 200. This code can also correct your queries, for example when you use the wrong domain name.

A 301 status error usually occurs when both the old and new locations of the service you are searching for are up to date.

404 — Page not found

404 error: page not found

The 404 (not found) status means that the page you are looking for simply does not exist — it has been deleted or never existed.

When you see such a code, you establish a connection to the server, but the server cannot find the file you requested. This is the most common error code.

500 & 505 Status Codes

500 internal server error

Code 505 is one of the types of server error codes. Along with error 503 (service unavailable) and code 500 (internal server error), it is one of the more common error statuses.

The 505 (version not supported) code itself means that the server refuses to support the indicated site or simply does not support it.

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