list of HTTP status codes

When a user visits a website using an Internet browser, the browser communicates with a server that handles browser requests. The server responds to the request with a certain action, either allowing the website to load or displaying an error message. Such actions are determined by the HyperText Transfer Protocol (HTTP). While there are 63 HTTP status codes in total, certain codes are fairly common (for example, the classic 404 “Not Found” error), while others rarely appear. Here are some of the most common HTTP status codes, which are named and numbered by the Internet Engineering Task Force (IETF) 9110 standard.

• 200 (OK): The request was successfully understood and accepted by the server.
• 301 (Moved Permanently): The Web address has been assigned a new URL, which is sometimes linked in the error message.
• 302 (Found): The Web address is temporarily under a different URL.
• 303 (See Other): The user is directed to a different website or resource by the server.
• 304 (Not Modified): When a Web page has not been modified since the last time a user accessed it, it may be more economical for the server to show the cached version, or the last saved copy, of the page. To determine whether the page has been modified, the server sends out a conditional request. If the page has not been modified, the server sends the 304 HTTP code and shows the cached Web page to the user. If the page has updated, the server sends the standard 200 code.
• 400 (Bad Request): The server cannot process the request due to a perceived client error.
• 401 (Unauthorized): The user is unable to access a URL, because the user lacks acceptable authentication credentials.
• 403 (Forbidden): Similar to a 401 error, this means the user is not authorized to access a URL. This error occurs following acceptable authentication credentials but indicates a lack of permission.
• 404 (Not Found): The server is currently unable to find a page for the URL. This differs from 410 (Gone), which indicates that the page is permanently gone.
• 500 (Internal Server Error): The server has encountered an unexpected error.
• 503 (Service Unavailable): The server is unavailable, possibly due to overloading, but this does not indicate permanent unavailability.