HTTP status codes are a tool used by web servers to return information about the state of a server and/or the information it is serving up to the browser. The codes are divided into 5 general classes, each of which is signified by the first of the three digits. 1xx codes are informational and indicate a response from the server, 2xx codes indicate successful communication with the server, 3xx codes correspond to redirection requests, 4xx codes indicate a client error, and 5xx codes indicate a server error.
Typically, the codes are processed transparently behind the scenes by your web browser. The only time a typical user will see the error codes are when they are in the 4xx and 5xx error-focused blocks. The most common of these errors is the infamous 404 page-not-found response.
- By Jason Fitzpatrick on 12/17/13