The Internet and the Web
▪ Greatest milestone in the development of computer technology is the Internet ▪ The Internet or Interconnection of Networks or Interconnected Networks is composed of various resources: ftp, telnet, usenet groups, e-mail, chat and instant messaging, and world wide web ▪ Internet provides an infrastructure by which the computers it connects (called hosts) can communicate. ▪ Internet cannot store info or provide services. Thus, for info and services to be accessible via the Internet, they must be stored or implemented on, or accessed via, the “hosts” or “SERVERS” ▪ The idea that computers request resources and others provide them is referred to as “Client/Server Architecture” ▪ Internet supports various types of servers: FTP servers, mail servers, gopher servers, and web servers ▪ The Internet has developed a subculture dedicated to the idea that the Internet is not owned or controlled by any one person, company, group, or organization ▪ Ray Tomlinson created in 1971 what was to become the standard Internet e-mail address format using the ‘@’ sign to separate user names from host names.
The Web Technology
▪ Web uses the Internet to provide facilities for storing information, finding and retrieving information, storing and executing computer programs, inputting and manipulating information ▪ Anyone with access to web can add any document and link it to any other existing document enabling the web to form a global, inter-linked information source ▪ Web is used for publicity and commercial and non-commercial purposes ▪ Web servers are computers that provide information and services that can be access on the Web (i.e. Apache, Microsoft’s Internet Information Services or IIS, Zeus, Sambar, iPlanet, Roxen, Jigsaw, etc.)
The World Wide Web
What is the World Wide Web?
▪ The World Wide Web (WWW) is most often called the Web.
▪ The Web is a network of computers all over the world.
▪ All the computers in the Web can communicate with each other. ▪ All the computers use a communication standard called HTTP.
How does the WWW work?
▪ Web information is stored in documents called Web pages. ▪ Web pages are files stored on computers called Web servers. ▪ Computers reading the Web pages are called Web clients. ▪ Web clients view the pages with a program called a Web browser. ▪ Popular browsers are Internet Explorer and Netscape Navigator.
How does the browser fetch the pages?
▪ A browser fetches a Web page from a server by a request. ▪ A request is a standard HTTP request containing a page address. ▪ A page address looks like this: http://www.someone.com/page.htm.
How does the browser display the pages?
▪ All Web pages contain instructions for display
▪ The browser displays the page by reading these instructions. ▪ The most common display instructions are called HTML tags. ▪ HTML tags look like this This is a Paragraph.
Who is making the Web standards?
▪ The Web standards are not made up by Netscape or Microsoft. ▪ The rule-making body of the Web is the W3C.
▪ W3C stands for the World Wide Web Consortium.
▪ W3C puts together specifications for Web standards.
▪ The most essential Web standards are HTML, CSS and XML. ▪ The latest HTML standard is XHTML 1.0.
Customer: "I don't have a computer. Is the internet available in book form?"
Introduction to HTML
What is an HTML File?
• HTML stands for Hyper Text Markup Language
• An HTML file is a text file containing small markup tags • The markup tags tell the Web browser how to display the page • An HTML file must have an htm or html file extension • An HTML file can be created using a simple text editor
An HTML 4 document is composed of three parts:
1. a line containing HTML version information,
2. a declarative header section (delimited by the HEAD...