The Internet, the Web and Email
How the Internet differs from the Web, IP addresses and DNS, the parts of a URL, HTTP versus HTTPS and status codes, browser cache and cookies, how email is sent and retrieved with SMTP, POP3 and IMAP, and the port numbers exams expect you to know.
What you will be able to do
- State the difference between the Internet and the World Wide Web.
- Explain how DNS turns a domain name into an IP address and name the parts of a URL.
- Describe what HTTPS adds over HTTP and read an HTTP status code by its family.
- Distinguish SMTP, POP3 and IMAP and recall the common port numbers.
What is inside this lesson
- 1Internet vs Web
- 2IP addresses and DNS
- 3The parts of a URL
- 4HTTP, HTTPS, status codes and ports
- 5How the browser helps and remembers
- 6How email works
- 7Worked example: from URL to page, and back to parts
- 8Common confusions
- 9Quick revision
- 10Practice
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Internet vs Web
The Internet is the global network of networks — the wiring, routers and addressing that let any two connected machines exchange data. It carries many services: the Web, email, file transfer, video calls, app traffic.
The World Wide Web is one service on the Internet: a system of linked pages and resources identified by URLs, fetched over HTTP and viewed in a browser. So every website uses the Internet, but email and a video call use the Internet without using the Web.
Most Internet services follow the client–server model: a client (your browser or mail app) sends a request; a server (a machine that hosts the site or mailbox) sends a response.
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