Architecture of the World Wide Web

Terms

web
a set of resources delivered over the Internet using the HTTP protocol
web resource
any information that can be accessed using the web (document, image, video)
web server
a software program on a computer that hosts web resources
web browser
an application used to acccess web resources on web servers

The web is distributed, addressable, and linked

Distributed

There is no centralised organisation or system that decides the content that can be published. Any computer connected to the Internet can run a web server and the person running it can make available any content they wish.

Addressable

Every resource on the web has a unique address that includes both its location and how to access it (URL):

  • scheme
    • specifies the [Application Layer](Application_Layer_of_Internet_Protocol.md for accessing the resource. In the example this is HTTP but it could be FTP or another protocol, always bracketed with a colon
  • authority
    • comprises the DNS hostname of the server containing the resource. This could also be an IP address and could also include a port number
  • path
    • the location of the resource on the web server, organised hierarchically and analagous to a file path
  • query
    • a modifier of the resource returned to the client. Its usage varies accross sites but is typically deterimined by backend implementation details

Note a URL does not have to always contain all this information. Consider an index page.

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