Internet
A browser makes the Internet feel like one direct connection: type a name, get a page. Underneath, the request travels through many pieces of infrastructure that only work because they agree on how to pass addressed messages along.
The Internet is not the same thing as the Web. The Internet is the shared network infrastructure. The Web is a service built on top of that infrastructure, using browsers, servers, URLs, domain names and DNS, and HTTP.
From a Local Network to the Internet
The smallest useful network is two computers connected so they can exchange messages. That does not scale by wiring every machine directly to every other machine.
A local network usually adds devices that specialize in moving messages:
| Device | Job |
|---|---|
| Switch | Moves messages inside a local network to the intended local device. |
| Router | Moves messages between separate networks. |
| Modem or access equipment | Adapts a local network to the provider's wider network. |
| ISP network | Connects many customer networks and exchanges traffic with other providers. |
The Internet is the result of many networks being connected this way. A message does not need one giant central switch. It needs a destination address and a chain of networks that can forward it closer to that destination.
Addresses and Names
Machines route traffic using IP addresses. People usually do not want to remember those addresses, and an address can change over time. A domain name gives people a stable, readable handle that can be resolved to an address when needed.
That name-to-address step is handled by DNS. Once the address is known, an application protocol such as HTTP can define what the two endpoints say to each other.
Why the Distinction Matters
When a website is slow or unreachable, the problem might be in several different layers: name resolution, routing, transport connection setup, the HTTP exchange, the server application, or a dependency behind that server.
Keeping the Internet/Web distinction clear helps debugging. The Internet gets messages between addressed machines. The Web defines one major family of services that run over it.