Http

Is a protocol use in every trasanction the World Wide Web.

HTTP is an TCP/IP based communication protocol, which is used to deliver data (HTML files, image files, query results etc) on the World Wide Web.

The default port is TCP 80, but other ports can be used.

It provides a standardized way for computers to communicate with each other.

HTTP specification specifies how clients request data will be constructed and sent to the serve, and how servers respond to these requests.

*define la sintaxis y la semántica que utilizan los elementos de software de la arquitectura web (clientes, servidores, proxies) para comunicarse*

Basic Features

- HTTP is connectionless:
      The HTTP client ie. browser initiates an HTTP request
            and after a request is made -> the client disconnects from the server and waits for a response.                     The server process the request and re-establish the connection with the client to send                            response back.

- HTTP is media independent:
       This means, any type of data can be sent by HTTP as long as both the client and server know how to handle the data content. This is required for client as well as server to specify the content type using appropriate MIME-type.

- HTTP is stateless:
       The server and client are aware of each other only during a current request. Afterwards, both of them forget about each other.
       Due to this nature of the protocol, neither the client nor the browser can retain information between different request across the web pages.

Basic Architecture
The HTTP protocol is a request/response protocol based on client/server based architecture where web browser, robots and search engines, etc. act like HTTP clients and Web server acts as server.

CLIENT
The HTTP client sends a request to the server in the form of a request method, URI, and protocol version, followed by a MIME-like message containing request modifiers, client information, and possible body content over a TCP/IP connection.
--- An HTTP "client" is a program (Web browser or any other client) that establishes a connection to a server for the purpose of sending one or more HTTP request messages. ---

SERVER
The HTTP server responds with a status line, including the message's protocol version and a success or error code, followed by a MIME-like message containing server information, entity metainformation, and possible entity-body content.
--- An HTTP "server" is a program ( generally a web server like Apache Web Server or Internet Information Services IIS etc. ) that accepts connections in order to serve HTTP requests by sending HTTP response messages. ---