WWW is a collection of millions of documents that are accessible through the Internet and that are stored (distributed) on millions of computers. A WWW document is referred to as a web page. A group of pages belonging to an organization or an individual is called a web site. The main page of a web site is called the homepage.

WWW uses the concept of hyperlink where a hyperlink is a piece of text (hypertext) or an image (hypermedia) that provides a link to another web page. Once a hyperlink is selected (clicked), the page it links (points to) is opened. A web page is written using a markup language that describes how the page should be displayed. Examples of markup language are HyperText Markup Language (HTML) and eXtended Markup Language (XML). To be accessible, each web page must have a unique address on the Internet. This address is called the uniform resource locator (URL). An example URL is http://www.sol.net.eg/sol/main.php, where HTTP stands for the HyperText Transfer Protocol which is the Internet protocol that is mostly used to provide the standards for accessing web pages.

Servers that provide web pages to those who request them are called web servers. The Internet has tens of thousands of web servers running. The web clients used to request web pages are called web browsers. Examples are Netscape Navigator and Microsoft’s Internet Explorer. Sometimes a web browser needs a special program, referred to as a plug-in, so as to be able correctly display a particular web page. Also, sometimes a web server stores a piece of text, referred to as a cookie, on the client’s computer so as to use it later when re-accessed by the client. For instance, assume that you are frequently accessing a web page that provides weather information. The server may store your home city as a cookie on your computer so that next time it will automatically provide you with your city’s weather information. If you are using Microsoft’s Internet Explorer to browse the web, look for cookies in the folder C:\WINDOWS\Cookies.