Why this matters
Almost nothing you do online happens on one machine alone. Sending a message, opening a website, printing at school: all of it depends on devices being wired (or wirelessly linked) into a network. Knowing the kinds of networks and the parts that build them is the foundation for everything else about the internet.
The idea
A computer network is a system that connects devices so they can swap data. Networks come in sizes:
- A LAN (local area network) covers a small area, like one home or one school. It can be wired (data travels through cables) or wireless (data travels by radio waves, no cables).
- A WAN (wide area network) reaches across a much larger area.
- The internet is the network that ties LANs and WANs together across the whole world.
To get a household onto the internet you sign up with an ISP (provider). Inside and between networks, two devices do the connecting: a hub gathers many cables into one central point, and a router passes data between different networks.
Once connected, computers take on roles. A server provides a service; a client asks for one. A file server stores files, a printer server handles printing, a mail server moves email, and a proxy server fetches the internet on your behalf. When machines split into providers and requesters this way it is a client-server system; when they are all equals helping each other, it is a peer-to-peer system.
Picture it
flowchart TD I[Internet: links networks worldwide] --- W[WAN: wide area] I --- L[LAN: home or school] L --- H[Hub: joins the cables] L --- R[Router: bridges to other networks] L --- S[Server: provides a service] L --- C[Client: requests a service]
Worked example
A school connects all its classroom computers in one building. Is that a LAN or a WAN? It is a single limited area, so it is a LAN. Now those computers need to reach a website on the other side of the world. The request leaves the LAN through a router, travels the internet, and reaches a server that sends the page back. The school's computer acting as the requester is the client.
Your turn
Try the practice questions: sort networks and devices into the right group, and match each device or role to what it does.
Recap
- A LAN is local, a WAN is wide, and the internet links them globally.
- A hub joins cables; a router bridges different networks; an ISP sells you access.
- A server provides, a client requests; that split is the client-server model.