How the Internet Works
Throughout this course you will build and ship the website of a small neighbourhood bakery, Crumb Bakery, at crumbbakery.com. Before writing a single tag, it helps to know what actually happens when someone in another city opens that site on their phone. The page does not fly across the world in one piece. It is chopped up, addressed and passed hand to hand.
The rule
Data travels as small addressed packets, hopping between networks, reassembled at the end.
A network of networks. Your home Wi-Fi is a small network. Your internet provider runs a bigger one. Universities, companies and cloud providers run their own. The internet is simply all of these networks agreeing to connect and to follow the same rules, called protocols. Nobody owns the whole thing.
Addresses. Every device that talks on the internet has an IP address, such as 203.0.113.10 (IPv4) or a longer IPv6 address like 2001:db8::10. It works like a postal address: it tells the network where to deliver.
Packets. Data is never sent as one big blob. It is split into packets of at most about 1,500 bytes on most networks, each labelled with the sender's and receiver's IP addresses. A photo of the bakery's sourdough might become hundreds of packets.
Routers. Along the way, routers read each packet's destination and pass it one hop closer. Packets from the same file can even take different routes.
Reassembly. At the far end, TCP (Transmission Control Protocol) puts the packets back in order, notices any that went missing and asks for those again. That is why a page arrives complete even though the network lost a few pieces on the way.
The two roles to remember:
- A client asks for something: your browser.
- A server answers: the computer holding the bakery's site.
The shortcut
When you picture any internet request, run the "post office" check: Who is sending? What is the address? How many parcels? Who puts them back together? If you can answer those four, you understand the trip.
The client asks
The phone's browser sends a small request to the server's IP address, split into packets that carry both addresses.
A common mix-up: the internet and the web are not the same thing. The internet is the network that moves packets. The web is one service that runs on top of it, made of linked pages fetched with HTTP. Email, video calls and online games also use the internet without being "the web".
Drills
Answer fast — trust the rule.
What best describes the internet?
What is an IP address for?
Three packets of the bakery's menu page are lost on the way. What normally happens?
Which of these uses the internet but is NOT part of the web?
Remember
- Data travels as small addressed packets, hopping between networks, reassembled at the end.
- Post office check: sender, address, parcels, reassembly.
- Trap: the internet moves packets; the web is just one service running on it.