Web Pages (Cambridge (CIE) IGCSE Computer Science)

Revision Note

Robert Hampton

Written by: Robert Hampton

Reviewed by: James Woodhouse

Loading a Web Page

How is a web page loaded?

  • Web pages are held on web servers (1), known as 'hosting'

  • To access a web page on a web server, a web browser is used

  • In the browser, a user enters a web page URL (2)

  • The browser sends the domain name to a DNS (3)

  • The browser connects to the web server and requests to access the page

  • HTML (4) is transferred and rendered by the browser, displaying the web page

Web Servers (1)

What is a web server?

  • A web server is a remote computer that stores the files needed to display a web page on the Internet

  • Web servers are generally available 24/7 and security is managed by the owner of the hardware

  • Web servers provide access to multiple users at the same time

Uniform Resource
Locator (URL) (2)

What is a URL?

  • A Uniform Resource Locator (URL) is a unique identifier for a web page, known as the website address

  • It is text based to make it easier to remember

  • A user enters a URL into a web browser to view a web page

  • An example of a URL is:

https://www.savemyexams.com/igcse/computer-science/cie/23/revision-notes/

  • A URL can typically be split into three parts:

    • Protocol

    • Domain name

    • Web page/file name

  • Using the example about the URL would be split as follows:

Protocol

https

Communication method to transfer data between client and server

Domain name

www.savemyexams.com

Name of the server where the resource is located

Web page/file name

/igcse/computer-science/cie/23/revision-notes/

Location of the file or resources on the server

Domain Name System (DNS) (3)

What is a DNS?

  • The Domain Name System (DNS) can be thought of as the Internet's equivalent to a phone book

  • It is essentially a directory of domain names and is used to translate human-readable domain names to the numeric  IP addresses that computers use

  • When you type a URL into your browser, the DNS translates the domain name into its associated IP address so your computer can connect to the server hosting the website

  • Without DNS, we would have to remember the IP address of every site we want to visit

HTML (4)

What is HTML?

  • Hypertext Markup Language (HTML), is the foundational language used to structure and present content on the web

  • HTML consists of a series of elements, often referred to as "tags"

  • Most tags are opened and closed e.g. <html> and </html>, whereas some tags are only opened e.g. <img> and <link>

Structure

  • HTML is used to define the basic structure of a webpage by organising content into sections such as headers, paragraphs, and footers

  • The <html> tag is the root element of an HTML page and includes all other HTML elements used to create a page structure

<!DOCTYPE html>
<html>
  <head>
    <title>My Web Page</title>
  </head>
  <body>
    <header>
      <h1>Welcome to My Website</h1>
    </header>
    <main>
      <section>
        <h2>About Me</h2>
        <p>This is a paragraph about me.</p>
      </section>
      <section>
        <h2>My Projects</h2>
        <p>This is a paragraph about my projects.</p>
      </section>
    </main>
    <footer>
      <p>Contact: [email protected]</p>
    </footer>
  </body>
</html>
  • In this example, HTML is used to create a structure with a header, two sections in the main body, and a footer

  • Other examples of HTML being used for structure include:

    • Creating lists to structure information

    • Positioning of text on the screen

    • Embedding media and interactive elements

Present

  • HTML is also used to present and display information in a visually meaningful way

  • The content layer of a web page is made up of HTML elements such as headings (<h1>, <h2>, etc.), paragraphs (<p>), links (<a>), images (<img>), and more

  • This layer is mainly handled by CSS (Cascading Style Sheets)

<!DOCTYPE html>
<html>
  <body>
    <h1>Welcome to My Website</h1>
    <p>This is a paragraph introducing the content of the website.</p>

    <h2>Subheading 1</h2>
    <p>Here is some detailed information under the first subheading.</p>

    <h2>Subheading 2</h2>
    <p>Another section with more information.</p>

    <p><strong>Bold text</strong> and <em>italic text</em> can emphasise important points.</p>
  </body>
</html>
  • In this example, headings (<h1>, <h2>) and text formatting tags (<strong>, <em>) are used to present the content clearly and with emphasis

  • Other examples of HTML being used to present information include:

    • Presenting data in a table

    • Displaying images with captions

Worked Example

A company sells products over the Internet.

Explain how the information stored on the company’s website is requested by the customer, sent to the customer’s computer and displayed on the screen.

[7]

Answer

Seven from:

Requested

  • a web browser is used

  • user enters the URL / web address (into the address bar) // clicks a link containing the web address // clicks an element of the webpage

  • the URL / web address specifies the protocol

  • protocols used are Hyper Text Transfer Protocol (HTTP) / Hyper Text Transfer Protocol Secure (HTTPS)

Sent

  • the URL / web address contains the domain name

  • the domain name is used to look up the IP address of the company

  • the domain name server (DNS) stores an index of domain names and IP addresses

  • web browser sends a request to the web server / IP address

Received

  • Data for the website is stored on the company’s web server

  • webserver sends the data for the website back to the web browser

  • web server uses the customer’s IP address to return the data

  • the data is transferred into Hyper Text Mark-up Language (HTML)

  • HTML is interpreted/rendered by the web browser (to display the website)

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Robert Hampton

Author: Robert Hampton

Expertise: Computer Science Content Creator

Rob has over 16 years' experience teaching Computer Science and ICT at KS3 & GCSE levels. Rob has demonstrated strong leadership as Head of Department since 2012 and previously supported teacher development as a Specialist Leader of Education, empowering departments to excel in Computer Science. Beyond his tech expertise, Robert embraces the virtual world as an avid gamer, conquering digital battlefields when he's not coding.

James Woodhouse

Author: James Woodhouse

Expertise: Computer Science

James graduated from the University of Sunderland with a degree in ICT and Computing education. He has over 14 years of experience both teaching and leading in Computer Science, specialising in teaching GCSE and A-level. James has held various leadership roles, including Head of Computer Science and coordinator positions for Key Stage 3 and Key Stage 4. James has a keen interest in networking security and technologies aimed at preventing security breaches.