What is the Internet?
The internet is the world's largest computer network — a massive global system that connects billions of devices together, including computers, phones, servers, smart TVs, and more. It carries emails, web pages, video streams, messages, and everything else that travels between computers around the world.
It is important to distinguish between the internet and the World Wide Web (WWW):
- The internet is the physical and logical infrastructure — cables, routers, and protocols.
- The Web is a service that runs on top of the internet — it is the collection of websites you access using a browser.
Email, video calls, online gaming, and streaming services all use the internet but are separate from the World Wide Web. The Web is just one of many services built on top of the internet.
How Data Travels
When you send a request — for example, loading a web page — your data does not travel as one big block. It is broken into small chunks called packets. Each packet travels independently across the network and may take a different route. When they all arrive, they are reassembled in the correct order.
This approach (called packet switching) is very efficient because:
- If one route is congested, packets can take an alternative path
- Multiple users can share the same network connections simultaneously
- A single broken link does not stop data getting through
Protocols: The Rules of Communication
For devices to communicate, they must agree on a set of rules. These rules are called protocols.
| Protocol | Purpose |
|---|---|
| TCP/IP | Core internet protocols — route and deliver packets reliably |
| HTTP/HTTPS | Transfer web pages between browser and server |
| DNS | Translate domain names (google.com) into IP addresses |
| SMTP | Send email |
| FTP | Transfer files between computers |
The Role of Routers
Routers are specialist devices that direct packets across the internet. When a packet arrives at a router, the router reads the destination IP address and decides the best next hop — the next router to send it to. Thousands of routers cooperate to find paths across the world.
Your home broadband router connects your home network to your ISP (Internet Service Provider), which in turn connects to the wider internet. Your ISP is your gateway to the global network.
DNS: The Internet's Phone Book
Humans remember names, not numbers. The Domain Name System (DNS) converts human-friendly names like www.bbc.co.uk into the numerical IP addresses that computers actually use. When you type a web address, your device first contacts a DNS server to look up the IP address, then connects to that address.
Practice Problems
Explain the difference between the internet and the World Wide Web. Give one example of an internet service that is not part of the Web.
Show answer
Why is packet switching more efficient than sending data as a single continuous stream? Give two reasons.