When a browser or search robot contacts the server with a request, it automatically receives a certain status code in response. Every HTTP status code is three-digit and can range from 100 to 526. The range is occasionally expanded to describe some new states, but it happens infrequently, so the server response codes described in this article will be enough in 99% of cases.
There are five categories of responses:
Let's take a closer look at the most common codes in each of these categories.
In response to the information codes do not need to send anything to the server, they are only needed to inform the receiving party about its status.
This group of server responses informs you that you need to initiate another request to a specific URL in order to proceed with the operation. The appropriate URL can be read in the Location header.
308 «Permanent Redirect» Reports that the requested resource has been permanently, i.e. permanently, moved to the URL specified in the Location header. Introduced in RFC 7238
Codes in this group report errors on the client side. As a rule, the message body contains a hypertext explanation for the user. Let's look at the main ones.
This group of server responses reports cases of unhandled exceptions found when attempting to perform a server-side operation.