HTTP

Updated: 07/06/2021 by Computer Hope
HTTP

Short for Hypertext Transfer Protocol, HTTP is a set of standards that allow users of the World Wide Web to exchange information found on web pages. When accessing any web page entering http:// in front of the address tells the browser to communicate over HTTP. For example, the URL for Computer Hope is https://www.computerhope.com. Today's browsers no longer require HTTP in front of the URL since it is the default method of communication. However, it is kept in browsers because of the need to separate protocols such as FTP.

HTTP overview

Below are a few of the major facts on HTTP.

  • The term HTTP was coined by Ted Nelson.
  • HTTP is a "stateless" protocol, meaning that every packet can be understood in isolation from any other, without the provision of additional session data.
  • The standard port for HTTP connections is port 80.
  • HTTP/0.9 was the first version of the HTTP, and was introduced in 1991.
  • HTTP/1.0 is specified in RFC 1945, and was introduced in 1996.
  • HTTP/1.1 is specified in RFC 2616, and was officially released in January 1997.
  • HTTP/2 is specified in RFC 7540, and was officially released on May 14, 2015. It improves page load times in the browser by compressing HTTP headers, and prioritizing and multiplexing data requests.
  • HTTP/3 is specified in a proposed RFC, with the goal of reducing data congestion by transmitting control messages over UDP. It was first supported in Chrome version 79 released on December 10, 2019, and Firefox version 72.0.1, released on January 8, 2020.

HTTPS (encrypted HTTP)

HTTPS

HTTPS, which stands for Hypertext Transfer Protocol Secure, is a protocol for transmitting HTTP over a connection that is encrypted by TLS (transport-layer security). HTTPS is used to protect transmitted data from eavesdropping. It's the default protocol for conducting financial transactions on the web, and can protect a website's users from censorship by a government or an ISP.

  • HTTPS uses port 443 to transfer its information.
  • HTTPS is first used in HTTP/1.1 and is defined in RFC 2616.
Tip

An https website has a URL that begins with https (like https://www.computerhope.com/). For browsers that do not show the front of the URL (e.g., Chrome) a lock icon or shield icon is shown. Also, you can double-click the URL on a computer to show the full URL.

What is S-HTTP?

Short for Secure HTTP, S-HTTP is an HTTP extension first developed in 1995 for allowing a secure (encrypted) method of transmitting files and messages between the client and server. Unlike SSL (secure sockets layer), S-HTTP allows the client to send a certificate as a form of authentication on a single message without establishing a secure connection first.

Tip

S-HTTP should not be confused with HTTPS. HTTPS is establishing a secure connection between two computer. S-HTTP is designed to send individual messages securely.

What are HTTP status codes?

404

Below is a listing of HTTP status codes currently defined by Computer Hope. These codes are error messages that allow a client accessing another computer or device over HTTP to know how to proceed or not proceed. For example, 404 tells the browser the request does not exist on the server.

Tip

These codes are also sometimes called HTTP return codes and web browser codes.

1xx - 2xx 3xx - 4xx 5xx
100 (Continue)
101 (Switch protocols)
102 (Processing)
200 (Success)
201 (Fulfilled)
202 (Accepted)
204 (No content)
205 (Reset content)
206 (Partial content)
207 (Multi-Status)
301 (Moved permanently)
302 (Moved temporarily)
304 (Loaded Cached copy)
307 (Internal redirect)
400 (Bad request)
401 (Authorization required)
402 (Payment required)
403 (Forbidden)
404 (Not found)
405 (Method not allowed)
406 (Not acceptable)
407 (Proxy authentication required)
408 (Request timeout)
409 (Conflict)
410 (Gone)
411 (Length required)
412 (Precondition failed)
413 (Request entity too large)
414 (Request URI too large)
415 (Unsupported media type)
416 (Request range not satisfiable)
417 (Expectation failed)
422 (Unprocessable entity)
423 (Locked)
424 (Failed dependency)
500 (Internal server error)
501 (Not Implemented)
502 (Bad gateway)
503 (Service unavailable)
504 (Gateway timeout)
505 (HTTP version not supported)
506 (Variant also negotiates)
507 (Insufficient storage)
510 (Not extended)

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