The World Wide Web

• Innovation is serendipity; inventors don't know what creations will result.
• Tim Berners-Lee is credited with this.
• http://www. is the World Wide Web's address.

The Advent of WWW

• The World Wide Web was invented at CERN (near Geneva, Switzerland) in 1989.
• British computer scientist Tim Berners-Lee was the inventor.
• Now, it revolutionizes worldwide communication.

What is the World Wide Web (WWW)

• A means to access information on the internet.
• Information is presented in web pages, viewed using a web browser.
• Web pages are interconnected using hypertext links.
• Clicking a link takes you to the related web page or resource.
• WWW isn't the entire internet; it's one internet service.

Client-Server Model

• Describes how networked computers interact.
• Clients request info from servers.
• Servers respond with the requested info (if available).
• Web servers use HTTP.
• File servers use FTP.

HyperText Transfer Protocol (HTTP)

• Method for requesting and transferring web pages.
• Communication happens through HTTP requests and responses.
• A user's click or URL input sends a request to a web server's HTTP port (80 or 8080).
• The server responds with the requested resource if valid and available.
• Otherwise, the server provides an error message.
• This exchange happens for all resources needed to display the page (images, video, etc.).

Ingredients for the Web

• Clients (Web browsers) use HTTP (GET or POST) to interact with web servers.
• HTML documents are requested and displayed.
• CSS (Cascading Style Sheets) controls presentation.
• JavaScript (JS) adds dynamic behavior.

Web Browsers

• Tim Berners-Lee created ENQUIRE (1980) and WorldWideWeb (1990).
• Mosaic (1993) was the first graphical user interface (GUI) browser.
• Netscape Navigator (1994) was the first commercial browser.
• Internet Explorer (1995) was developed by Microsoft.
• Firefox (2002) was developed by Mozilla.
• Safari (2003) was developed by Apple.
• Google Chrome (2008) surpassed other browsers.
• Microsoft Edge (2016) was created by Microsoft.

Search Engines

• Systems that search and catalog (index) web page content.
• Users input search criteria; the engine finds matching content.
• Search criteria can be text and use Boolean operators for specificity.
• Results can be filtered.

Web Authoring

• Building web pages.
• HTML is the language to build web pages.

HyperText Markup Language (HTML)

• Defines web page content as a text file (.html).
• Tags define content characteristics.
• Text within tags is displayed as is.
• < > tags are used for open, close tags.
• Tags can specify additional attributes.
• Web page text is in the HTML file; other content (images) is linked.
• Pages link to each other, making a web of interconnected content.

"What You See Is What You Get" Software

• WYSIWYG (What You See Is What You Get) software shows the finished form in the editor.
• Examples of WYSIWYG software include most text editors, Microsoft Word, Excel, PowerPoint, Gimp, Audacity.

Example of a Simple Web Page

• A basic example of an HTML file is presented.
• URLs are used to show page locations.

Basic Structure of a Web Page

• : The outline for the HTML document.
• : Holds information like author and keywords.
• : Contains the page content.
• Tags use spacing and indentation for human readability.

Some HTML Tags

• ...

  : Paragraph.
• 
  : Forced line break.

• ---

  : Horizontal rule.
• ...
  : Unordered list.
• ...
  : Ordered list.
• ...
: List item.

• ...

  ,

  ...

  , etc.: Headings.
• ...
  : Division or section, with special characteristics.
• : Image display.
• ...: Hypertext link.
• : Comments for descriptions and notes.

Tag Attributes

• Provide additional characteristics to tags.
• Tag attributes have the form: attrName="value".
• Examples:
• ...
  : center-aligned content.
• : Image with dimensions.
• York University : hyperlinked URL.

Web Page

• HTML (Content & Structure): e.g., headings, paragraphs, lists.
• CSS (Presentation): e.g., font, color, background.
• JavaScript (Behavior): e.g., dynamic displays, user interactions.

Cascading Style Sheets (CSS)

• CSS describes how HTML elements are displayed.
• Defines styles for text, background, images, etc.
• Controls the layout of multiple pages.
• CSS can be added in three ways: inline, internal, and external.
• Separate CSS files are a common way to manage styles.

Inline CSS, Internal CSS and External CSS

• Styles are used to define look and layout of HTML pages.

Simple CSS Example

• Shows a simple CSS example in an HTML file.

Tim Berners-Lee

• The web is for social connection, not just technical use and innovation.
• Its goal is to support improvements in the world through connection and trust.
• The Magna Carta for the web will protect people's rights online.

Edward Snowden

• Discusses the need for digital rights and the values we should protect online.

Explore the origins and functionalities of the World Wide Web in this quiz. Learn about Tim Berners-Lee's invention, the client-server model, and how information is accessed through web pages. Test your knowledge on HTTP and the interconnected nature of the web.