HTTP (for HyperText Transfer Protocol) is the primary method used to convey information on the World Wide Web. The original purpose was to provide a way to publish and receive HTML pages. The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet runs. ... The application layer is the seventh level of the seven-layer OSI model. ... The File Transfer Protocol (FTP) is a software standard for transferring computer files between machines with widely different operating systems. ... HTTPS is the secure version of HTTP, the communication protocol of the World Wide Web. ... The Internet Message Access Protocol (commonly known as IMAP, and previously called Interactive Mail Access Protocol) is an application layer Internet protocol used for accessing email on a remote server from a local client. ... Internet Relay Chat (IRC) is a form of instant communication over the Internet. ... The Network News Transfer Protocol or NNTP is an Internet application protocol used primarily for reading and posting Usenet articles, as well as transferring news among servers. ... Post Office Protocol version 3 (POP3) is an application layer Internet standard protocol used to retrieve email from a remote server to a local client over a TCP/IP connection. ... Session Initiation Protocol (SIP) is a protocol developed by the IETF MMUSIC Working Group and proposed standard for initiating, modifying, and terminating an interactive user session that involves multimedia elements such as video, voice, instant messaging, online games, and virtual reality. ... Simple Mail Transfer Protocol (SMTP) is the de facto standard for email transmission across the Internet. ... The Simple Network Management Protocol (SNMP) forms part of the internet protocol suite as defined by the Internet Engineering Task Force. ... In computing, Secure shell or SSH is both a computer program and an associated network protocol designed for logging into and executing commands on a networked computer. ... Telnet is a network protocol used on the Internet or local area network LAN connections. ... BitTorrent is the protocol and the name of the peer-to-peer (P2P) file distribution tool written by programmer Bram Cohen and debuted at CodeCon 2002. ... WebSphere MQ [1] (known as MQSeries until 2002) is IBMs Message Oriented Middleware offering. ... The Datagram Congestion Control Protocol (DCCP) is a message-oriented transport layer protocol that is currently under development in the IETF. Applications that might make use of DCCP include those with timing constraints on the delivery of data such that reliable in-order delivery, when combined with congestion control, is... The Stream Control Transmission Protocol (SCTP) is a transport layer protocol defined in 2000 by the IETF Signaling Transport (SIGTRAN) working group. ... The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. ... The Real-time Transport Protocol (or RTP) defines a standardized packet format for delivering audio and video over the Internet. ... Ethernet, Wi-Fi, Token ring, FDDI, PPP RS-232, EIA-422, RS-449, EIA-485, 10BASE2, 10BASE-T... The User Datagram Protocol (UDP) is one of the core protocols of the Internet protocol suite. ... Internet Light is a transport layer communication protocol designed at Bell Labs for the 9P protocol in Plan 9. ... The Reliable User Datagram Protocol (RUDP) is a transport layer protocol designed at Bell Labs for the Plan 9 operating system. ... The network layer is level three of the seven level OSI model. ... IPv4 is version 4 of the Internet Protocol (IP). ... This article may be confusing for some readers, and should be edited to enhance clarity. ... The data link layer is level two of the seven-level OSI model. ... Ethernet (this name comes from the physical concept of ether) is a frame-based computer networking technology for local area networks (LANs). ... Wi-Fi (sometimes written Wi-fi, WiFi, Wifi, wifi) is a trademark for set of product compatibility standards for wireless local area networks (WLANs). ... Token-Ring local area network (LAN) technology was developed and promoted by IBM in the early 1980s and standardised as IEEE 802. ... In computer networking, fiber-distributed data interface (FDDI) is a standard for data transmission in a local area network that can extend in range up to 200 km (124 miles). ... In computing, the Point-to-Point Protocol, or PPP, is commonly used to establish a direct connection between two nodes. ... The physical layer is level one in the seven level OSI model of computer networking. ... RS-232 (also referred to as EIA RS-232C or V.24) is a standard for serial binary data interchange between a DTE (Data terminal equipment) and a DCE (Data communication equipment). ... EIA-422 (formerly RS-422) is a serial data communication protocol which specifies 4 wire, full-duplex, differential line, multi-drop communications. ... RS-449 - Wikipedia /**/ @import /skins/monobook/IE50Fixes. ... EIA-485 (formerly RS-485 or RS485) is an OSI Model Physical layer electrical specification of a two-wire, half-duplex, multipoint serial connection. ... 10BASE2 cable showing BNC Connector end. ... FUCK！ ... In computing, hypertext is a user interface paradigm for displaying documents which, according to an early definition (Nelson 1970), branch or perform on request. ... This article concerns communication between pairs of electronic devices. ... Graphic representation of the World Wide Web around Wikipedia The World Wide Web (WWW, W3, or simply Web) is an information space in which the items of interest, referred to as resources, are identified by global identifiers called Uniform Resource Identifiers (URIs). ... In computing, HyperText Markup Language (HTML) is a markup language designed for the creation of web pages and other information viewable in a browser. ...

Development of HTTP was co-ordinated by the World Wide Web Consortium and working groups of the Internet Engineering Task Force, culminating in the publication of a series of RFCs, most notably RFC 2616, which defines HTTP/1.1, the version of HTTP in common use today. The World Wide Web Consortium (W3C) is a consortium that produces the software standards (recommendations, as they call them) for the World Wide Web. ... The Internet Engineering Task Force (IETF) is charged with developing and promoting Internet standards. ... A Request for Comments (RFC) document is one of a series of numbered Internet informational documents and standards very widely followed by both commercial software and freeware in the Internet and Unix communities. ...

HTTP is a request/response protocol between clients and servers. An HTTP client, such as a web browser, typically initiates a request by establishing a TCP connection to a particular port on a remote host (port 80 by default). An HTTP server listening on that port waits for the client to send a request string, such as "GET / HTTP/1.1" (which would request the default page of that web server), followed by an email-like MIME message which has a number of informational header strings that describe aspects of the request, followed by an optional body of arbitrary data. Some headers are optional, while others (such as Host) are required by the HTTP/1.1 protocol. Upon receiving the request string (and message, if any), the server sends back a response string, such as "200 OK", and a message of its own, the body of which is perhaps the requested file, an error message, or some other information. A web browser is a software application that enables a user to display and interact with HTML documents hosted by web servers or held in a file system. ... The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. ... In computing, a port (derived from seaport) is usually a connection through which data is sent and received. ... The term web server can mean one of two things: a computer responsible for serving web pages, mostly HTML documents, via the HTTP protocol to clients, mostly web browsers; a software program that is working as a daemon serving web documents. ... Multipurpose Internet Mail Extensions (MIME) is an Internet Standard for the format of e-mail. ...

HTTP request methods

• GET By far the most common, for statically requesting a resource by specifying a URL.
• POST Similar to GET, except that a message body, typically containing key-value pairs from an HTML form submission, is included in the request.
• PUT Used for uploading files to a specified URI on a web-server.
• DELETE Rarely implemented, and self-explanatory.
• HEAD Identical to GET, except that the page content is not returned; just the headers are. Useful for retrieving meta-information.
• TRACE Echoes back the received request, so that a client can see what intermediate servers are adding or changing in the request.
• OPTIONS Returns the HTTP methods that the server supports. This can be used to check the functionality for a web server.
• CONNECT Rarely implemented, for use with a proxy that can change to being an SSL tunnel.

HTTP differs from other TCP-based protocols such as FTP, in that connections are usually terminated once a particular request (or related series of requests) has been completed. This design makes HTTP ideal for the World Wide Web, where pages regularly link to pages on other servers. It can occasionally pose problems for Web designers, as the lack of a persistent connection necessitates alternative methods of maintaining users' "state". Many of these methods involve the use of cookies. A Uniform Resource Identifier (URI), is an Internet protocol element consisting of a short string of characters that conform to a certain syntax. ... Secure Sockets Layer (SSL) and Transport Layer Security (TLS), its successor, are cryptographic protocols which provide secure communications on the Internet. ... This page is about the File Transfer Protocol, a computer protocol. ... A HTTP magic cookie (usually called simply a cookie) is a packet of information sent by a server to a World Wide Web browser and then sent back by the browser each time it accesses that server. ...

HTTPS is the secure version of HTTP, using SSL/TLS to protect the traffic. The protocol normally uses TCP port 443. SSL, originally created to protect HTTP, is especially suited for HTTP since it can provide (some) protection even if only one side to the communication, the server, is authenticated. This is typically the case in HTTP transactions over the Internet. HTTPS is the secure version of HTTP, the communication protocol of the World Wide Web. ... Secure Sockets Layer (SSL) and Transport Layer Security (TLS), its successor, are cryptographic protocols which provide secure communications on the Internet. ...

The locations of HTTP (and HTTPS) pages are given as Uniform Resource Locators or URLs. This address location syntax was created for linking Web pages. A Uniform Resource Locator, URL (spelled out as an acronym, not pronounced as earl), or Web address, is a standardized address name layout for resources (such as documents or images) on the Internet (or elsewhere). ...

Sample

Below is a sample conversation between an HTTP client and an HTTP server running on www.example.com, port 80.

Client request:

 GET / HTTP/1.1 Host: www.example.com 

(followed by a double new line, each in the form of a carriage return followed by a line feed.) In computing, a newline is a special character or sequence of characters signifying the end of a line of text. ... Originally, carriage return was the term for the key, lever, or mechanism on a typewriter that would cause the cylinder on which the paper was held (the carriage) to return to the left side of the paper after a line of text had been typed, and would often move it... In computing, line feed (LF) is a control character indicating that one line should be fed out. ...

The "Host" header distinguishes between various DNS names sharing a single IP address. While optional in HTTP/1.0, it is mandatory in HTTP/1.1. The Domain Name System or DNS is a system that stores information about hostnames and domain names in a type of distributed database on networks, such as the Internet. ... An IP address (Internet Protocol address) is a unique number, similar in concept to a telephone number, used by devices (usually computers) attached to a network to refer to each other when sending information through a Local LAN, Wide area WAN or the Internet networks. ...

Server response:

 HTTP/1.1 200 OK Date: Mon, 23 May 2005 22:38:34 GMT Server: Apache/1.3.27 (Unix) (Red-Hat/Linux) Last-Modified: Wed, 08 Jan 2003 23:11:55 GMT Etag: "3f80f-1b6-3e1cb03b" Accept-Ranges: bytes Content-Length: 438 Connection: close Content-Type: text/html; charset=UTF-8 

(followed by a blank line and text of the requested page)

Connection persistence

In HTTP/1.0, a client sends a request to the server, the server sends a response back to the client. After this, the connection is closed. HTTP/1.1, however, supports persistent connections. This enables the client to send a request and get a response, and then send additional requests and get additional responses immediately. The TCP connection is not released for the multiple additional requests, so the relative overhead due to TCP is much less per request. It is also possible to send more than one (usually two) request before getting responses from previous requests. This technique is known as "pipelining".

See also

• List of HTTP status codes
• 404 error
• Uniform resource locator
• Basic authentication scheme
• Digest access authentication
• Captive portal
• HTTP proxy
• Content negotiation

// Status codes The following is a list of HTTP status codes. ... Netscape Navigator displaying the 404 error page at eBay The 404 or Not Found error message, as commonly encountered when using a web browser on the World Wide Web, is a manifestation of one of the standard response codes of the Webs principal communication protocol, HTTP. When communicating via... A Uniform Resource Locator, URL (spelled out as an acronym, not pronounced as earl), or Web address, is a standardized address name layout for resources (such as documents or images) on the Internet (or elsewhere). ... In the context of a HTTP transaction, the basic authentication scheme is a method designed to allow a web browser, or other client program, to provide credentials – in the form of a user name and password – when making a request. ... Digest access authentication is one of the agreed methods a web page can use to negotiate credentials with a web user (using the HTTP protocol). ... The captive portal technique forces an HTTP client on a network to see a special web page (usually for authentication purposes) before surfing the Internet normally. ... A proxy server is a computer network service which allows clients to make indirect network connections to other network services. ... Content negotiation is a mechanism defined in the HTTP specification that makes it possible to serve different versions of a document (or more generally, a resource) at the same URL, so that user agents can choose which version fit their capabilities the best. ...

External links

Specifications and references

• HTTP/1.0 specification (May 1996) as plain text: RFC 1945
• HTTP/1.1 specification (June 1999) as plain text: RFC 2616; also as HTML, as PostScript, and as PDF;
• HTTP/1.1 specification errata
• Tim Berners-Lee's original 1992 Internet-Draft
• HTTP Sequence Diagram (PDF)

Sir Tim Berners-Lee Sir Tim (Timothy John) Berners-Lee, KBE (TimBL or TBL) (b. ...

Tutorials and tools

• HTTP Made Really Easy
• HTTP header viewer
• HTTP Header Check - Bookmarklet
• View HTTP Request and Response Header
• Command-line HTTP clients: cURL, Wget, Snarf, fetch
• HTTP Request Smuggling
• HTTP compression