How the Internet Works: From Your Device to a Website

The internet is not a single machine, a company or a cloud floating somewhere. It is a very large number of separate networks, owned by different organizations, that have agreed to use the same rules so that they can pass data to one another. Your home network is one of them. A university network is another. A company that runs web servers has its own.

This entry gives the big picture: who and what sits between your device and a website, and why data can cross the world in a fraction of a second. Details such as addresses, names and web requests each have their own entries, and this page points to them.

A network of networks

A network is a group of devices that can exchange data. Your phone, laptop and printer at home form a small network. The internet joins networks like this together, which is why it is often called a "network of networks". The word itself comes from "inter-network".

No one owns the whole thing. Thousands of organizations run their own parts: internet providers, universities, governments, cloud companies and businesses. They connect their networks at meeting points and agree to pass each other's traffic along. RFC 1958, a document from the standards community about the internet's design, describes the goal as connectivity and the tool that achieves it as the Internet Protocol, a rule set that works no matter what kind of cable or radio carries the data.

The internet is not the web

These two words get mixed up. The internet is the global system of connected networks. The web is one service that runs on it, made of pages and sites you open in a browser. Email, video calls, online games and software updates also travel over the internet without being part of the web. The web gets its own walkthrough in what happens when you open a web page.

The path from your device

Follow the data from a laptop in a living room to a website. Each stop has a clear role.

Your home equipment is covered in home network basics. The important point here is that your ISP is your door to everything else. It connects to other, bigger networks, and those connect onward. Long-distance links use fiber-optic cables on land and under the sea, plus radio and satellite links in places where cables are impractical.

Packets and routers: how data is sent

Packets

Data does not travel as one big block. It is cut into small pieces called packets. Each packet carries a piece of the content plus a label with the sending address and the receiving address. Other protocols, such as TCP, add the numbering that lets the pieces be put back in order.

An everyday comparison is sending a long book by post in many small envelopes, each numbered, instead of one huge parcel. The envelopes may take different routes and arrive in a different order. The receiver sorts them by number and rebuilds the book. If one envelope is lost, only that one needs to be sent again.

This design has two advantages. Many people can share the same links, because packets from different conversations are mixed together. And if one link fails, packets can be sent another way.

Routers: the traffic directors

A router is a device that connects networks and decides where each packet goes next. It reads the destination address on the packet, checks its knowledge of the neighboring networks and forwards the packet to the best next step. That step is called a hop. The next router repeats the process, and so on, until the packet reaches the network that holds the destination.

No single router knows the whole route. Each one only decides the next hop. The approach is similar to asking for directions in a city, one junction at a time. The original definition of the Internet Protocol describes the same idea: gateways forward datagrams between networks. The address that these decisions are based on is explained in what an IP address is.

Rules that everyone shares: protocols

For two computers made by different companies to understand each other, they follow shared rules called protocols. A protocol is an agreement about the format and order of messages. Protocols work in layers, each solving one problem:

• Moving data across networks. The Internet Protocol (IP) addresses and forwards packets.
• Making delivery dependable. Another protocol, TCP, numbers the pieces, checks that all of them arrived and asks for missing ones again.
• Talking about a particular service. HTTP, for example, is the language of web pages, and other protocols exist for email and file transfer.

Because the rules are public and shared, any device that follows them can join the internet. That openness is a main reason it grew so quickly.

Servers, data centers and names

A server is a computer that waits for requests and answers them. Websites, email and streaming services all run on servers. Many servers are placed together in data centers, which are buildings with fast connections, power backup and cooling. Large services often copy their content to several places, so a visitor is served from a location nearer to them.

You usually type a name, such as example.com, not a number. Before your device can send packets, it needs the address behind that name, and a worldwide lookup system finds it. That system is explained in what DNS is.

A worked example: sending a photo

Say you send a photo from your phone to a friend in another country through a messaging app.

1. The app splits the photo into many packets and labels each with the address of the messaging company's server.
2. The packets leave your phone over Wi-Fi to your home router.
3. The router passes them to your ISP, which forwards them hop by hop through larger networks.
4. They reach the server of the messaging company, which puts the pieces back together.
5. The server then sends the photo, again as packets, over its own route to your friend's device, which rebuilds it.

At no point does one machine hold the whole route. Each stop only knows the next step, and the shared rules make the pieces fit.

Common mistakes

• Treating the internet and the web as the same thing. The web is only one of many services that use the internet.
• Picturing "the cloud" as nowhere. Cloud data still sits on real servers in real buildings, owned by a company.
• Blaming the website for every slowdown. Speed depends on your Wi-Fi, your provider, the route and the server. Test with another site first.
• Thinking one organization controls the internet. Many groups run separate parts, and standards bodies publish the shared rules.
• Assuming a private message travels in a straight line. Packets pass through many networks. Encryption, not distance, is what protects the content.

FAQ

Who owns the internet?

No one. Many organizations own and operate separate networks, and they cooperate through shared standards and agreements.

How does data cross the ocean?

Mostly through fiber-optic cables laid on the sea floor, which carry data as pulses of light. Satellites carry a smaller part of traffic.

Is Wi-Fi the same as the internet?

No. Wi-Fi is a way to connect your device to your local network without a cable. The internet is what that network connects to through your provider.

Why does a website sometimes load slowly?

The cause can be your Wi-Fi signal, a busy network, a distant or overloaded server, or a heavy page. Trying other sites helps you tell which one it is.

Where should I go next?

Start with what an IP address is, then the other entries in the Computing and Networks area. Each one zooms into one part of the picture above.