The web is a wide-scale decentralised distributed hypertext system, something that's obviously impossible to achieve reliably.
The web is a collection of resources which are identified by
URLs, strings starting with
http://. At any point in
time, a resource has a certain value, which is called an
instance of the resource.
The fundamental protocol of the web is HTTP, a simple request/response protocol. With HTTP, a client can make a request for a resource to a server, and the server replies with an entity, which is an on-the-wire representation of an instance or of a fragment thereof.