Q.Identify some other networks in the real world.

A network, in the general sense used here, is any set of nodes connected by links along which something flows — a pattern visible in many everyday systems besides computer networks. …

What makes something a network?

If you can name these five things, you are looking at a network.

Networks in the real world

1. Road network. Nodes = cities and junctions; links = roads and highways; the flow = vehicles. The rules of the road (traffic signals, lane discipline, speed limits) are its protocol, and a traffic jam is exactly what a computer network calls congestion.

2. Railway network. Nodes = railway stations; links = tracks; the flow = trains. Junction stations act as routers, deciding which line a train takes next. Indian Railways is among the largest such networks in the world.

3. Airline network. Nodes = airports; links = flight routes; the flow = aircraft and passengers. Airlines deliberately use a hub-and-spoke design (many small airports feeding a few large hubs), which is the real-world twin of the star topology.

4. Telephone / mobile network. Nodes = handsets, landlines and cell towers; links = copper, fibre and radio; the flow = voice and data. This is the network that historically inspired computer networking — the very idea of switching a call comes from here.

5. Electricity grid. Nodes = power stations, substations, homes; links = transmission lines; the flow = electric power. Its mesh design is why a single failed line usually does not black out a city — the same redundancy argument used for mesh topology in computer networks.

6. Water supply and drainage. Nodes = reservoirs, overhead tanks, taps; links = pipes; the flow = water. Water pressure is its "bandwidth", and a burst pipe is a link failure.

7. Postal and courier network. Nodes = post offices and sorting hubs; links = trucks, trains and planes; the flow = letters and parcels. A pin code is an address, sorting is routing, and a parcel travelling hub to hub is precisely store-and-forward packet switching.

8. Social network. Nodes = people; links = friendships, family ties, professional contacts; the flow = information (and gossip). Online platforms merely digitise a network that always existed.

9. Banking / ATM network. Nodes = bank branches, ATMs, payment switches; links = secure leased lines; the flow = transactions. Withdrawing cash from any bank's ATM works because those machines are internetworked.

10. Biological neural network. Nodes = neurons; links = synapses; the flow = electrical impulses. This network is the direct inspiration for artificial neural networks in AI.

Comparing them with a computer network