1.1 Introduction to Web Applications

	Web applications are evolved from websites or web systems. The first created websites in 1990 by CERN
	physicist Tim Berners-Lee. He formed a distributed hypermedia system which enabled researchers to have
	access to documents and information published by other researchers directly from their computers.

	Web browser is the piece of software runs on a client computer that enables users to access and view
	documents. To view a document, the following steps are performed:

		The user enters the name of the document in the browser and the name of the host computer where it can
		be found.

A request is sent from the browser to the host computer where a web server can handle a request.

		The web server in turn receives the request, locates the document on its local file system, and sends it back
		to the browser.

Figure 1.1: Basic website

1.1 Introduction to Web Applications

	When the resources (e.g. documents, audio, video...etc) are linked to each other it forms a hypermedia system
	or what is called a web system. A web system looks like a spider web, resources are connected to one another,
	and user can navigate easily between the resources.

	A web application extends a web system to add business functionality, which means that a web application is a
	website that allows its users to execute business logic with a web browser.

Nowadays, web applications are the most popular applications all over the word for the following reasons:

Accessibility anyone with a web browser has the ability to access an application.

		Cheap the cost of updating and maintaining web applications is very low. You don't have to distribute or
		install software on potentially thousands of client computers.

Portability as it rely on the inherent, web applications are supported a cross-platform.

	Common examples of web applications include webmail (e.g. Hotmail, Gmail, and Yahoo!), online retail sales
	(e.g. amazon.com), social applications (e.g. Facebook, Twitter and Youtube), wikis (e.g. wikipedia.org) and
	many other applications.